Question: What was expanded by the US bicameral legislature by the Federal-Aid Highway Act of 1968?

full_context: Document 1: Federal-Aid Highway Act of 1952: The Federal-Aid Highway Act of 1952 authorized $25 million for the Interstate Highway System on a 50–50 matching basis, meaning the federal government paid 50% of the cost of building and maintaining the interstate while each individual state paid the balance for interstate roads within their borders.
Document 2: Federal-Aid Highway Act of 1944: The Federal-Aid Highway Act of 1944 (Pub. L. No. 78-521; 58 Stat. 838) is legislation enacted by the United States Congress and signed into law on December 20, 1944, which established a 50-50 formula for subsidizing the construction of national highways and secondary (or "feeder") roads. The legislation established a National System of Interstate Highways, and required the Public Roads Administration to establish construction and operational standards for the Interstate Highway System.
Document 3: United States Senate chamber: The United States Senate Chamber is a room in the north wing of the United States Capitol that serves as the legislative chamber of the United States Senate, since January 4, 1859. The Senate first convened in its current meeting place after utilizing Federal Hall, Congress Hall, and the Old Senate Chamber in the Capitol building for the same purpose.
Document 4: Federal-Aid Highway Act of 1973: The Federal-Aid Highway Act of 1973 (Public Law 93–87; 87 Stat. 250) is legislation enacted by the United States Congress and signed into law on August 13, 1973, which provided funding for existing interstate and new urban and rural primary and secondary roads in the United States. It also funded a highway safety improvement program, and permitted states for the first time in U.S. history to use Highway Trust Fund money for mass transit. The law also established the first national speed limit (of 55 mph ).
Document 5: List of African-American United States Senators: The United States Senate has had ten African-American elected or appointed office holders. The United States Senate is the upper house of the bicameral United States Congress, which is the legislative branch of the federal government of the United States. The US Census Bureau defines African Americans as citizens or residents of the United States who have origins in any of the black populations of Africa. The term is generally used for Americans with at least partial ancestry in any of the original peoples of sub-Saharan Africa. During the founding of the federal government, African Americans were consigned to a status of second-class citizenship or enslaved. No African American served in federal elective office before the ratification in 1870 of the Fifteenth Amendment to the United States Constitution. The Fifteenth Amendment prohibits the federal and state governments from denying any citizen the right to vote because of that citizen's race, color, or previous condition of servitude. Of the ten senators, six were popularly elected (including one that previously had been appointed by his state's governor), two were elected by the state legislature prior to the ratification of the Seventeenth Amendment to the United States Constitution in 1913 (which provides for the direct election of U.S. Senators by the people of each state), and two were appointed by a state Governor. The 113th United States Congress (2013–15) marked the first time that two African Americans served concurrently in the Senate.
Document 6: Federal Aid Highway Act of 1956: The Federal-Aid Highway Act of 1956, popularly known as the National Interstate and Defense Highways Act (Public Law 84-627), was enacted on June 29, 1956, when President Dwight D. Eisenhower signed the bill into law. With an original authorization of US$25 billion for the construction of 41,000 miles (66,000 km) of the Interstate Highway System supposedly over a 10-year period, it was the largest public works project in American history through that time.
Document 7: Federal-aid highway program: The U.S. federal-aid highway program was commenced in 1916, with milestones of Federal-Aid Highway Act of 1944 and Federal Aid Highway Act of 1956.
Document 8: Federal-Aid Highway Act of 1968: The Federal-Aid Highway Act of 1968 (Public Law 90-495; 82 Stat. 815) is legislation enacted by the United States Congress and signed into law on August 24, 1968, which expanded the Interstate Highway System by 1500 mi ; provided funding for new interstate, primary, and secondary roads in the United States; explicitly applied the environmental protections of the Department of Transportation Act of 1966 to federal highway projects; and applied the Davis–Bacon Act to all highway construction funded by the federal government. It established three new programs: a National Bridge Inspection Program, funding and fair housing standards for those displaced by federally funded highway construction, and a traffic operations study program.
Document 9: Civil Rights Act of 1968: The Civil Rights Act of 1968, (Pub.L. 90–284 , 82 Stat. 73 , enacted  11, 1968 ), also known as the Fair Housing Act, is a landmark part of legislation in the United States that provided for equal housing opportunities regardless of race, religion, or national origin and made it a federal crime to “by force or by threat of force, injure, intimidate, or interfere with anyone … by reason of their race, color, religion, or national origin.” The Act was signed into law during the King assassination riots by President Lyndon B. Johnson, who had previously signed the Civil Rights Act and Voting Rights Act into law.
Document 10: 112th United States Congress: The One Hundred Twelfth United States Congress was a meeting of the legislative branch of the United States federal government, from January 3, 2011, until January 3, 2013. It convened in Washington, D.C. on January 3, 2011, and ended on January 3, 2013, 17 days before the end of the presidential term to which Barack Obama was elected in 2008. Senators elected to regular terms in 2006 completed those terms in this Congress. This Congress included the last House of Representatives elected from congressional districts that were apportioned based on the 2000 census.
Document 11: 1st United States Congress: The First United States Congress, consisting of the United States Senate and the United States House of Representatives, met from March 4, 1789, to March 4, 1791, during the first two years of George Washington's presidency, first at Federal Hall in New York City and later at Congress Hall in Philadelphia. With the initial meeting of the First Congress, the United States federal government officially began operations under the new (and current) frame of government established by the 1787 Constitution. The apportionment of seats in the House of Representatives was based on the provisions of of the Constitution. Both chambers had a Pro-Administration majority. Twelve articles of amendment to the Constitution were passed by this Congress and sent to the states for ratification; the ten ratified as additions to the Constitution on December 15, 1791, are collectively known as the Bill of Rights.
Document 12: United States Congress: The United States Congress is the bicameral legislature of the federal government of the United States consisting of two chambers: the Senate and the House of Representatives.
Document 13: Historic Preservation Fund: The National Historic Preservation Act of 1966 (NHPA) envisioned a funding source to provide states with matching funds to implement the Act. The Act was to be implemented through partnerships with states, Indian Tribes, Native Hawaiians, local governments, nonprofit organizations, and the private sector. It brought forth state programs to implement much of the Act; a National Register of Historic Places encompassing a wide range of sites and structures deemed historic; partnerships at all levels of government; incentives; assistance; and reviews. The NHPA endorsed the use of federal financial support for the national preservation program and called for two basic categories of assistance, both of which provide funding, rather than technical assistance, for historic preservation projects and to individuals for the preservation of properties listed in the National Register of Historic Places. Since enactment in 1966, repeated efforts to fund the HPF was realized after a 10-year campaign when consistent funding was authorized on September 28, 1976, through Public Law 94-422. The law amended the National Historic Preservation Act to establish a funding source known as the Historic Preservation Fund for a historic preservation grant program to provide assistance to non-federal entities.
Document 14: 113th United States Congress: The One Hundred Thirteenth United States Congress was a meeting of the legislative branch of the United States federal government, from January 3, 2013, to January 3, 2015, during the fifth and sixth years of Barack Obama's presidency. It was composed of the United States Senate and the United States House of Representatives based on the results of the 2012 Senate elections and the 2012 House elections. The seats in the House were apportioned based on the 2010 United States Census. It first met in Washington, D.C. on January 3, 2013, and it ended on January 3, 2015. Senators elected to regular terms in 2008 were in the last two years of those terms during this Congress.
Document 15: Upper house: An upper house, sometimes called a Senate, is one of two chambers of a bicameral legislature (or one of three chambers of a tricameral legislature), the other chamber being the lower house. The house formally designated as the upper house is usually smaller, and often has more restricted power, than the lower house. Examples of upper houses in countries include the UK's House of Lords, India's Rajya Sabha, Russia's Federation Council, Ireland's Seanad, Germany's Bundesrat and the United States Senate.
ground_truth: Interstate Highway System