Pembina is a city in Pembina County, North Dakota in the United States. The population was 642 at the 2000 census. Pembina is the oldest community in the Dakotas. A fur-trading post was established on the site of present-day Pembina in 1797 and the first permanent settlement started in 1812. Until 1823, Pembina was thought to be in Canada, but in that year United States Army Major Stephen H. Long's survey of the 49th parallel revealed Pembina's location south of the Canada – United States border. The first post office in present-day North Dakota was established in Pembina in 1851. Pembina served as county seat from 1867 to 1911. Pembina is near the northern end of Interstate 29 at the Canada-United States border at Emerson, Manitoba. It is a significant crossing for road traffic headed to and from Winnipeg, Manitoba and is one of three 24-hour ports of entry in North Dakota. Pembina is home to the U.S. satellite plant of Motor Coach Industries, which completes assembly of intercity buses, for customers including Greyhound Lines.