U.S. president Richard Nixon visits the Soviet Union.

Richard Milhous Nixon (January 9, 1913 April 22, 1994) was the 37th president of the United States, serving from 1969 to 1974. Known as Richard M. Nixon for most of his career, he was a member of the Republican Party who previously served as a representative and senator from California and was the 36th vice president from 1953 to 1961. His five years in the White House saw reduction of U.S. involvement in the Vietnam War, dtente with the Soviet Union and China, the first manned Moon landings, and the establishment of the Environmental Protection Agency. Nixon's second term ended early, when he became the only president to resign from office, following the Watergate scandal.

Nixon was born into a poor family of Quakers in a small town in Southern California. He graduated from Duke Law School in 1937, practiced law in California, then moved with his wife Pat to Washington in 1942 to work for the federal government. After active duty in the Naval Reserve during World War II, he was elected to the House of Representatives in 1946. His work on the Alger Hiss Case established his reputation as a leading anti-Communist, which elevated him to national prominence, and in 1950, he was elected to the Senate. Nixon was the running mate of Dwight D. Eisenhower, the Republican Party's presidential nominee in the 1952 election, and served for eight years as the vice president. He ran for president in 1960, narrowly lost to John F. Kennedy, then failed again in a 1962 race for governor of California, after which time it was widely believed that his political career was over. However, in 1968, he made another run for the presidency and was elected, narrowly defeating Hubert Humphrey and George Wallace in a close contest.

Nixon ended American involvement in Vietnam combat in 1973, and with it, the military draft, that same year. His visit to China in 1972 eventually led to diplomatic relations between the two nations, and he also then concluded the Anti-Ballistic Missile Treaty with the Soviet Union. In step with his conservative beliefs, his administration incrementally transferred power from the federal government to the states. Nixon's domestic policy saw him impose wage and price controls for 90 days, enforce desegregation of Southern schools, establish the Environmental Protection Agency, and begin the War on Cancer. Additionally, his administration pushed for the Controlled Substances Act and began the War on Drugs. He also presided over the Apollo 11 Moon landing, which signaled the end of the Space Race. He was re-elected with a historic electoral landslide in 1972 when he defeated George McGovern.

In his second term, Nixon ordered an airlift to resupply Israeli losses in the Yom Kippur War, a war which led to the oil crisis at home. By late 1973, the Nixon administration's involvement in Watergate eroded his support in Congress and the country. On August 9, 1974, facing almost certain impeachment and removal from office, Nixon resigned the presidency. Afterwards, he was issued a pardon by his successor, Gerald Ford. In his almost 20 years of retirement, Nixon wrote his memoirs and nine other books and undertook many foreign trips, rehabilitating his image into that of an elder statesman and leading expert on foreign affairs. He suffered a debilitating stroke on April 18, 1994, and died four days later at age 81. Surveys of historians and political scientists have ranked Nixon as a below-average president. However, evaluations of him have proven complex, as the successes of his presidency have been contrasted with the circumstances of his departure from office.

The president of the United States (POTUS) is the head of state and head of government of the United States of America. The president directs the executive branch of the federal government and is the commander-in-chief of the United States Armed Forces.

The power of the presidency has grown substantially since the office's establishment in 1789. While presidential power has ebbed and flowed over time, the presidency has played an increasingly strong role in American political life since the beginning of the 20th century, with a notable expansion during the presidency of Franklin D. Roosevelt. In contemporary times, the president is also looked upon as one of the world's most powerful political figures as the leader of the only remaining global superpower. As the leader of the nation with the largest economy by nominal GDP, the president possesses significant domestic and international hard and soft power.

Article II of the Constitution establishes the executive branch of the federal government and vests the executive power in the president. The power includes the execution and enforcement of federal law and the responsibility to appoint federal executive, diplomatic, regulatory, and judicial officers. Based on constitutional provisions empowering the president to appoint and receive ambassadors and conclude treaties with foreign powers, and on subsequent laws enacted by Congress, the modern presidency has primary responsibility for conducting U.S. foreign policy. The role includes responsibility for directing the world's most expensive military, which has the second largest nuclear arsenal.

The president also plays a leading role in federal legislation and domestic policymaking. As part of the system of checks and balances, Article I, Section 7 of the Constitution gives the president the power to sign or veto federal legislation. Since modern presidents are also typically viewed as the leaders of their political parties, major policymaking is significantly shaped by the outcome of presidential elections, with presidents taking an active role in promoting their policy priorities to members of Congress who are often electorally dependent on the president. In recent decades, presidents have also made increasing use of executive orders, agency regulations, and judicial appointments to shape domestic policy.

The president is elected indirectly through the Electoral College to a four-year term, along with the vice president. Under the Twenty-second Amendment, ratified in 1951, no person who has been elected to two presidential terms may be elected to a third. In addition, nine vice presidents have become president by virtue of a president's intra-term death or resignation. In all, 45 individuals have served 46 presidencies spanning 58 full four-year terms.Joe Biden is the 46th and current president of the United States, having assumed office on January 20, 2021.