This is a list of ambassadors from the United States to Canada. The ambassador is the head of the Embassy of the United States in Ottawa.

Prior to 1943, the head of the U.S. diplomatic mission to Canada bore the title of Envoy Extraordinary and Minister Plenipotentiary. The U.S. mission to Canada was upgraded from legation to embassy status in June 1943, and Ray Atherton was the first chief of mission to hold ambassadorial rank.

This is a list of ambassadors of the United States to individual nations of the world, to international organizations, to past nations, and ambassadors-at-large.

Ambassadors are nominated by the President and confirmed by the Senate. An ambassador can be appointed during a recess of the Senate, but can serve only to the end of the next session of Congress unless subsequently confirmed by the Senate. Ambassadors serve "at the pleasure of the President," which means that they can be dismissed at any time.

An ambassador may be a career foreign service officer or a political appointee. In most cases, U.S. ambassadors who are career foreign service officers serve a tour of approximately three years in a foreign post. Ambassadors who are political appointees will customarily tender their resignations upon inauguration of a new President. As embassies fall within the Department of State, ambassadors answer to the Secretary of State.

Current ambassadors from the United States to international organizations

The United States of America (commonly abbreviated to the United States, the U.S., the USA, America, and the States) is a federal constitutional republic comprising fifty states and a federal district. The country is situated mostly in central North America, where its forty-eight contiguous states and Washington, D.C., the capital district, lie between the Pacific and Atlantic Oceans, bordered by Canada to the north and Mexico to the south. The state of Alaska is in the northwest of the continent, with Canada to the east and Russia to the west, across the Bering Strait. The state of Hawaii is an archipelago in the mid-Pacific. The country also possesses several territories in the Pacific and Caribbean.

At 3.79 million square miles (9.83 million km²) and with over 312 million people, the United States is the third or fourth largest country by total area, and the third largest by both land area and population. It is one of the world's most ethnically diverse and multicultural nations, the product of large-scale immigration from many countries. The U.S. economy is the world's largest national economy, with an estimated 2011 GDP of $15.1 trillion (22% of nominal global GDP and over 19% of global GDP at purchasing-power parity). Per capita income is the world's sixth-highest.

Canada ( /ˈkænədə/) is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean. Spanning over 9,900,000 km² (3,800,000 sq mi), Canada is the world's second-largest country by total area, and its common border with the United States is the longest land border in the world.

The land that is now Canada has been inhabited for millennia by various Aboriginal peoples. Beginning in the late 15th century, British and French colonial expeditions explored, and later settled, along the region's Atlantic coast. France ceded nearly all of its colonies in North America in 1763 after the Seven Years' War. In 1867, with the union of three British North American colonies through Confederation, Canada was formed as a federal dominion of four provinces. This began an accretion of provinces and territories and a process of increasing autonomy; the Canada Act 1982 severed the vestiges of legal dependence on Britain.

David Horton Wilkins (born October 12, 1946) is an American attorney and a former U. S. Ambassador to Canada during the administration of President George W. Bush. Prior to the appointment, he practiced law for 30 years while serving in the South Carolina House of Representatives for 25 of those years. He was speaker of the South Carolina House for 11 years. Wilkins presently chairs the public policy and international law practice department of a large South Carolina law firm.

A life-long resident of South Carolina, Wilkins graduated from Greenville High School, attended Clemson University on a tennis scholarship, and graduated cum laude with a bachelor's degree in 1968. He earned his law degree from the University of South Carolina and then served in the Army as a first lieutenant. In the early 1970s, he returned to Greenville, where he and his wife, Susan, raised their two sons.

Wilkins, a Republican, was first elected to the South Carolina House of Representatives in 1980. He quickly rose through the ranks of the Democratically-controlled House, serving six years as chairman of the Judiciary Committee and two years as speaker pro tem before being elected speaker, a position he held for 11 years. He was the first Republican to elected speaker of any legislative body in the South since Reconstruction and when he retired on June 2, 2005, he was the third longest serving speaker in South Carolina history.