​The first attempt to establish a civil government in Oregon was in 1841, when American settlers met to determine how to probate the estate of wealthy entrepreneur Ewing Young. An executive committee and a committee to draft a code of laws were formed. The attempt at government failed due to pressure from British interests and cautions from Lieutenant Charles Wilkes, of the U. S. Exploration Expedition, who warned that the attempt was premature. 

Two years later, Oregon's residents formed a provisional government at public meetings in Champoeg in May and July, 1843. At the May 2 meeting, a 9-member legislative committee was created to draft a code of laws for the provisional government. On May 16, the committee created sub-committees for ways and means, military affairs, private land claims, and for the division of counties. The committee also established operating rules. 

The Organic Act ratified at the public meeting of July 5, 1843, was based on the Iowa State Law Code and included a bill of rights and a land law. It established a unicameral legislature consisting of 9 elected members apportioned to the counties by population. The legislature, known as the legislative committee, was required to meet twice a year, in June and in December. The legislative committee created 4 counties, instituted a voluntary subscription method for government funding, established a judicial system, set up a militia, and designated the method for claiming land. 

The first provisional legislative session was held in Oregon City, June, 1844. A sub-committee on roads was added to the existing standing sub-committees. The house met for a special session in December, 1844. The second regular session of the legislative committee was held June, 1845. The number of legislators increased to 12. Three new standing sub-committees were created at this session: claims, elections, and Indian affairs. 

The Organic Act of 1845 defined the legislative branch and renamed it the house of representatives. The house was to consist of at least 13 members and no more than 61 members. Members were popularly elected and vacancies filled by special election. The house was given the power to impeach all civil officers by a three-fourths majority vote. The legislature had the power to create counties, apportion legislators, levy taxes, require licenses, regulate white-Indian trade, establish post offices, declare war, organize the militia, call out the militia, regulate liquor manufacture and sales, regulate currency, regulate the internal police, create lower courts, and pass laws for the general welfare of the people of Oregon. The house was required to meet on the first Tuesday in December. 

From 1845 until 1848, the number of legislators increased from 13 to 20. In the 1848 session 23 members were apportioned, but only 9 met; the rest were digging gold in California. New members were appointed and 18 members convened the session on Dec. 5, 1848.

The Act of Congress of Aug. 14, 1848, which created Oregon Territory, significantly revised the legislative branch of government. The territorial legislature, known as the Legislative Assembly, was made a bicameral body. It consisted of a nine-member Council and eighteen-member House of Representatives. The House could be increased in size, but could not exceed 30 members. Legislators were popularly elected and vacancies were filled by special election. Legislative sessions were limited to 60 days. The Legislative Assembly was prohibited from passing laws interfering with land claims and passing laws which taxed non-residents at a higher rate than residents. The Legislative Assembly was also prohibited from incorporating banks and financial institutions and from acquiring debts in the name of the territory. 

Laws passed by Legislative Assembly were to deal with one subject only, named in the title, and had to be approved by Congress. Without both conditions, laws passed were considered null and void. The Act of Congress affirmed all laws passed by the provisional House of Representatives which were not in conflict with its provisions and required the Legislative Assembly to locate the territorial capital at its first session. 

The first session of the territorial Legislative Assembly convened in Oregon City, July, 1849. A special session was held in May, 1850 to set times for convening regular legislative sessions. The first Monday in December was chosen. The second regular session was Dec. 2, 1850. The Legislative Assembly passed legislation making Salem the territorial capital. This law became the central issue in a political controversy. Two Supreme Court justices refused to recognize the legality of the act relocating the capital and held a Dec., 1851 Supreme Court session in Oregon City. One Supreme Court justice and the Legislative Assembly convened Dec., 1851 sessions in Salem. It wasn't until May, 1852, when Congress legalized the capital's move to Salem, that the territorial government functioned normally.

Gov. John P. Gaines called a special session of the Legislative Assembly in July, 1852. To spite the Whig governor, the Democratic legislature convened on July 26 and adjourned on July 29, refusing to conclude any business. The 1852 regular session convened December 6 and passed legislation creating new counties north of the Columbia, transferring the right to grant divorces from the Legislative Assembly to the court system, and chartering Willamette University. 

The sixth regular session convened Dec. 4, 1854. On Jan. 13, 1855, it passed legislation making Corvallis the territorial capital. The seventh session was held in Corvallis. The territorial governor and treasurer remained in Salem after the U. S. Treasury Department ruled the move illegal. The legislature convened in Corvallis on December 3. It passed only one act - moving the capital back to Salem - before it adjourned. The Legislative Assembly reconvened in Salem on December 18. On December 30, the newly-built capitol building burned. The session was concluded in the Rector Building in downtown Salem. 

The Oregon Constitutional Convention was held in Salem from Aug. 17 to Sept. 18, 1857. After some dissension over slavery, free blacks, education, and state boundaries, the Oregon Constitution was put to a vote of the people on Nov. 9, 1857. It was approved by a vote of 7,195 in favor and 3,215 opposed. 

Elections were held June, 1858 to elect legislators in compliance with the ratified constitution. Two full sets of legislators were elected, one territorial and the other state. The Legislative Assembly met according to the constitution on July 5, 1858 to choose U. S. Senators and to inaugurate the state governor, secretary of state, and treasurer. Congress delayed acting on Oregon's statehood, so no state legislative session was held in 1858. The territorial Legislative Assembly convened Dec. 6, 1858 and adjourned Jan. 22, 1859 without accomplishing much. Oregon became a state on Feb. 14, 1859 and the state's first legislative session, a special session, was held May, 1859.

At the first special session of the Legislative Assembly held after statehood, laws were passed to organize the state government. The first regular session was convened on Sept. 10, 1860. The Legislative Assembly continued to meet on the second Monday in September until 1885. Because fall sessions were an inconvenience to farmer-legislators, sessions were moved to the winter and since 1885 the Legislative Assembly has convened in Salem on the second Monday in January of odd-numbered years. 

Throughout the 19th and early 20th centuries legislative sessions averaged 40 days in length. Beginning in the 1920s the length of sessions has gradually increased; during the 1980s the average session length has been 6 months. 

The Legislative Assembly consists of two houses, the House of Representatives and the Senate. Senators are elected to four-year terms, half of which are filled every other year. Representatives are elected to two-year terms. Senators and representatives are elected from single-member districts with an average population in 1990 of 44,000 for House districts and 88,000 for Senate districts. The first Legislative Assembly consisted of 16 senators and 34 representatives. However, due to population increases, as early as 1872 each house had reached its constitutional limit of 30 senators and 60 representatives. 

The Legislative Assembly has met biennially since 1860 with the exception of the 1897 session which was never held. A power struggle between factions of the Republican party became intertwined with progressive legislation and the election of the United States senator. Political maneuvering, led by Representative William S. U'Ren, prevented the Legislative Assembly from organizing. This precluded the passage of legislation and the election of a senator that biennium. 

Because the Legislative Assembly meets biennially, the need arises at times to deal with emergencies, especially financial emergencies, that occur when the Legislative Assembly is not in session. To deal with fiscal matters without calling a special session, the Emergency Board​ was created in 1913. The Emergency Board authorizes the allocation and expenditure of funds by agencies beyond originally appropriated amounts from an emergency fund, approves budgets for new activities, and revises agency budgets. It originally included the governor, secretary of state, and treasurer, but the composition of this board has been revised over the years.

According to a legislative guide, The Oregon Legislature, 1989, the Legislative Assembly functions to "enact new laws and revise existing ones relating to the health, education and general welfare of Oregonians, and to make decisions that keep the state in good economic and environmental condition." The Legislative Assembly interacts with the public and serves as a forum for the resolution of group conflict and the expression of public grievances. The Legislative Assembly also reviews administrative rules drafted by state agencies and the Senate confirms certain executive appointments made by the governor. 

The Legislative Assembly derives most of its power from its responsibility to administer the state's budget, and from its taxation and appropriation powers. The Legislative Assembly establishes priorities and sets public policy by exercising its power to allocate state funds. It also decides how state funds will be spent. 

Until the late 1960s, budgetary politics was largely conducted by the Legislative Assembly and state agencies. Governor Tom McCall, 1967-1975, was the first governor to play an active role in the budget process. 

The most powerful committee in the Legislative Assembly is the Joint Ways and Means Committee, which holds concentrated financial power. Composed of members from both the Senate and House, the Joint Ways and Means Committee controls the budget process by reviewing all legislation to determine how to use state revenue while maintaining a constitutionally mandated balanced budget.

To carry out responsibilities, the Legislative Assembly has a well-organized committee system which dominates the legislative process by considering and revising bills and other measures. Most work of formulating legislation and setting public policy is done in committees. In the 1971 Legislative Assembly, for example, only 2% of all bills favorably recommended by a committee failed to receive enough votes on the floor.

Significant power is retained by the presiding officers in each house, the speaker of the House and the president of the Senate. The speaker and president wield considerable power over committees because they have authority to determine committees, appoint committee members and chairpersons, decide which bills go to which committees, guide debate on the floor, and appoint conference committees when necessary. The president and speaker are assisted by pro tempores and party affairs are managed by majority and minority leaders in both houses.​​

​ Standing Committees function while Legislative Assembly is in session primarily to consider legislation which has been referred to a committee according to subject matter. The committee holds meetings and public hearings, debates and revises measures, and makes recommendations to the full chambers. 

Task Forces are special legislative groups formed for a limited period to study one problem or topic. 

Interim Committees are created jointly by both houses and serve between sessions. They hold public meetings, study areas that may require legislative solutions, prepare reports, and make recommendations to the next Legislative Assembly. 

Statutory Committees function during both regular and interim sessions. The primary function of these committees, which are created by statute, is to study proposals for legislation and provide continuity for the legislature from session to session. The most powerful statutory committee is the Emergency Board​. The Legislative Assembly may also create Special Committees for specified purposes; Conference Committees to resolve differences between the houses on legislative matters; and the rarely used Committee of the Whole to consider legislation under informal procedures.

Carrying out the business of the Legislative Assembly has become more complicated and technical, extending throughout the years. This is due to the growth of Oregon's population and increasingly complex social issues, growing citizen group involvement, a more active federal role in state affairs, and expansion of state government functions. 

The traditional structure of Oregon government has been a legislative assembly which meets biennially and is served by part-time, citizen legislators. Since World War II there have been periodic investigations and reports made by interim committees to examine government organization and legislative procedures with recommendations for more efficient handling of bills and better management of legislator and committee time. 

The reduction in the number of committees has served to decrease the workload on senators and representatives. From between thirty to forty committees in each house in the 1930s and 1940s, the number of committees has been reduced to fifteen in each house in 1989. Other suggestions that have been rejected include increasing the number of legislators, reducing the length of the legislative session, adopting annual legislative sessions, and electing adequately compensated full-time, professional legislators. The committees have looked to other means to make the Legislative Assembly more efficient. Two significant changes that have improved legislative efficiency are the Legislative Counsel Committee and the Legislative Fiscal Office. 

Created in 1953, the Legislative Counsel Committee, which consists of the legislative counsel and legal and clerical staff, drafts measures for legislators, legislative committees, and state agencies. The Legislative Assembly had relied on interim committees to investigate issues and prepare reports, but part-time legislators did not have time to conduct in-depth research into legislative problems. 

The Legislative Fiscal Office was created in 1959 to assist legislators and committees. The legislative fiscal officer is responsible to the Joint Ways and Means Committee and the Emergency Board. The staff of fiscal officers make recommendations to the Legislative Assembly concerning state expenditures, the budget, and fiscal implications of the organization and functions of state agencies. 

Other statutory committees and interim offices assisting the Legislative Assembly are the Legislative Administration Committee, the Oregon Law Commission, the Legislative Revenue Committee, the Joint Legislative Audit Committee, the Legislative Commission on Indian Services, the Joint Committee on Information Management and Technology, and the Committee on Executive Appointments.

In the early 20th century, Oregon acquired a national reputation for its progressive program of direct participation by the electorate in the legislative system. This direct legislation came to be known as the "Oregon System." Political maneuvering during the 1897 legislative session provided the progressive leader, William S. U'Ren, with the support needed for his direct legislation program. For the first time since its adoption in 1857, the state constitution was amended in 1902 to provide for the initiative and referendum. Additional legislation passed in the next 10 years included the direct primary in 1904, the direct election of U.S. senators in 1906, the recall of public officials in 1908, the presidential preference primary in 1910, and woman's suffrage in 1912. By exercising direct legislation options, the Oregon public had a significant impact on the Legislative Assembly and state government. 

Direct legislation was frequently used in the first 2 decades of the 20th century. Early usage included an initiative to restrain corporations and improve the condition of working people. Progressive measures included banking and securities regulation, a railroad commission, regulation of hours and conditions of female and child labor, a minimum wage, workers compensation, and home rule for cities. Although frequently used, direct legislation made limited adjustments to contemporary problems. Radical change, such as nationalization of railroads, the single tax, and restructuring of state government, failed as did measures requiring extensive appropriations. 

According to the 1999-2000 Oregon Blue Book, the initiative has been used 288 times and the referendum 61 times. The initiative has been used unwisely, as in 1922, when an initiative measure was passed to close parochial and private schools. Supported by the Ku Klux Klan, which had become politically powerful in the early 1920s, the school bill reflected the conservatism and racism of the time. Although the Legislative Assembly passed the measure in 1923, the Supreme Court declared it unconstitutional in 1925. 

Other examples of the use of the initiative include the creation in 1984 of the Citizens' Utility Board, a watchdog group to represent the interests of electricity, gas, and telephone consumers; and the Oregon Scenic Waterways Act of 1970 to protect segments of designated rivers.

The progressive tradition of direct legislation and the state's fiscal conservatism are defining characteristics of the Oregon political system. Constitutional requirements along with voter insistence that tax measures be referred to them has meant the Legislative Assembly must work closely with the electorate to gain support for tax increases. 

The Legislative Assembly has had to amend the state constitution in order to fund state programs. In the 1930s the construction of a new State Library building required a constitutional amendment. Economic conditions brought on by the Great Depression left little room in the state budget for this building. In 1935 the federally funded Public Works Administration provided funds for a new building, but because of constitutional limitations, the state was unable to accept the money. The 1939 Legislative Assembly passed legislation enabling the state to accept federal aid, including WPA funds for the present library building on the capitol mall.

In 1933, 1936, and 1945 extensive areas of forest in NW Oregon were burned in a series of devastating forest fires known as the Tillamook Burn. A constitutional amendment was ratified in 1948 to provide funds to finance the rehabilitation and reforestation of burned areas.

One of the most important areas of domestic legislation in Oregon is environmental and natural resource legislation. Oregon has been in the forefront nationally and internationally in forest management practices. As early as 1911 the Department of Forestry was established to reduce damage from forest fires on private lands. The 1929 Oregon Reforestation Law, the forerunner of other reforestation laws in the 1940s and 1970s, was considered one of the most progressive forestry laws in the U.S.

Throughout the 20th century, forestry laws have been enacted relating to the acquisition of land, fighting and prevention of forest fires, rehabilitation and reforestation of forests damaged by fire and logging, and forest and land management. 

The Oregon Forest Practices Act of 1971, which replaced a 30-year-old forest conservation act, was the first law of its kind in the U.S. to regulate forest operations while protecting the forest environment. The act established rules for timber operators and landowners concerning timber harvesting, use of chemicals, slash disposal, reforestation, road construction and maintenance, and other activities that have an impact on the soil, fish and wildlife, and water in Oregon's forests. 

Oregon has been innovative in the area of land use planning. As early as 1899 the beaches in Clatsop County were declared a public highway. In 1913 similar rights of public access to all Oregon beaches were established. A statewide planning program was established in 1973 and later revised in 1987. In order to protect Oregon's natural resources and provide for orderly development, a Land Conservation and Development Commission was established. Cities and counties in Oregon were required to adopt comprehensive plans that met mandatory state standards and planning goals. In 1987 all regulation of forest and land use practices were placed within the Forest Practices Act. 

After World War II, environmental issues continued to dominate political affairs in Oregon and create national interest in legislation to protect the environment. The late 1960s and 1970s were an active time for the passage of natural resource legislation. 

The Oregon Beach Laws of 1967 and 1969 protected the public's right of access to the free and uninterrupted use of Oregon ocean beaches and regulated the use of motor vehicles on the beaches. 

The Scenic Waterways Act of 1970 was designed to protect and enhance the natural, esthetic, scenic, fish and wildlife, scientific, and recreational values of segments of designated rivers and ensure they remain free-flowing without dams or other impoundments. 

In 1971 the Bottle Bill​ provided for a 5¢ refund for bottles and cans and prohibited the use of detachable openings for soft drink and beer cans. 

The Oregon Recreation Trails System Act of 1971 required that bicycle and footpath trails be built and maintained wherever a highway, road, or street was constructed or relocated. It also made provisions for trails in urban areas and near scenic areas. Oregon law requires 1% of highway funds be spent on footpaths and bikeways annually. The Advisory Committee on Bicycles was established in 1973 to advise the Highway Department on regulation of bicycle traffic and the establishment of bicycle lanes and paths. 

The Willamette River Park System Act of 1967 and the Willamette River Greenway Act of 1973 were enacted to maintain and enhance the scenic, recreational, and historical qualities of land along the Willamette River. 

Other examples of environmental legislation are the regulation of field burning and the ban on the sale of aerosol sprays in 1977. 

Carey, Charles Henry, editor. The Oregon Constitution and Proceedings and Debates of the Constitutional Convention of 1857. Printed under the direction of the Oregon Historical Society, 1926. 

Dodds, Gordon B. Oregon: A Bicentennial History. New York: W.W. Norton & Company, Inc., 1977. 

Edwards, Cecil L. Alphabetical List of Oregon's Legislators and Related Information Provisional Government to Present. Published by the Legislative Administration Committee, 1993. 

Edwards, Cecil L. Chronological List of Oregon's Legislatures. Published by the Legislative Administration Committee, 1993. 

Handbook on the Oregon Legislature. Legislative Counsel Committee, 1972. 

Isseks, Morris S. History of State Administrative Agencies in Oregon, 1843-1937. Published under the auspices of the Works Progress Administration, 1939. 

Legislative Media Services. The Oregon Legislature, 1993. Salem: Legislative Administration Committee, 1993. 

Oregon Bluebook, 2005-2006. Compiled and published by the Secretary of State, 2005. 

Pierce, Lawrence C., Richard G. Frey, and S. Scott Pengelly. The Freshman Legislator: Problems and Opportunities, A Handbook on the Oregon Legislature. American Political Science Association, 1972. 

Report of the House Rules and Procedures Task Force. House of Representatives, Sixtieth Legislative Assembly, 1978. 

State Government Organization. Second Report of the Legislative Interim Committee on State Government Administration, Forty-sixth Legislative Assembly, 1951.

State Government Organization in Oregon, 1958: Proposal for a Progressive and Continuing Program of Reorganization. Report of the Legislative Interim Committee on Government Reorganization, 1958. 

Terminal Report of the Interim Committee on Changes in Legislative Procedure. 46th Oregon Legislative Assembly, 1952