Only after the 49th parallel had been designated as the Canadian-American border (in 1846) was it realized that the tiny town of Point Roberts would be cut off from the rest of America:
(from Wikipedia)
A geopolitical oddity, Point Roberts [known locally as "Point Bob" or "The Point"; population 1,300] is a part of the mainland United States but is not physically connected to it, making it a pene-exclave of the U.S. It is located on the southernmost tip of the Tsawwassen Peninsula, south of Delta, British Columbia, Canada, and can be reached by land from the rest of the United States only by traveling through Canada. ....
The red dot is Point Roberts
In 1949, there was talk about Point Roberts seceding from the U.S.A. and joining Canada, but this never happened. In 1973, a drought caused the wells to run dry and created tensions between the American and Canadian residents of Point Roberts. The Americans threatened to cut off the Canadian residents' water supply — and hung up signs saying "Canadians Go Home" — unless the Canadian district of Delta agreed to provide water to Point Roberts, an arrangement that became permanent in 1986. ....
Because of having to go through the international border twice to get to the rest of the U.S.A., some have called it "the best gated community in the U.S." Residents enjoy a low crime rate at the cost of a high local security presence and other inconveniences. There is no hospital, doctor, dentist, pharmacist, or veterinarian ...
The only school in Point Roberts (K - 3rd)
Point Roberts Primary School, the only school on the Point, provides only kindergarten and first, second and third grades. From fourth grade on, American children must take a 40-minute ride through British Columbia, crossing back into the United States at Blaine, Washington.