The closest Canadian city to the US border is Surrey, located in British Columbia. It is part of the Greater Vancouver area and shares a border with the US state of Washington.
The closest southern neighbor would be Mexico.
That would depend on where you are, which you didn't include in the question.
Chile is the southern hemisphere country that is closest to the US. Both countries have territories near the 90°W line of longitude at their closest points.
Asia (Russia) is about 100 miles from the US (Alaska)
mt hood
Billings, Montana (population 104,934) is the closest major city with a population of over 100,000. Gateway communities for Yellowstone National Park include Livingston, MT; Gardiner, MT; Cooke City, MT; Jackson, WY; Cody, WY; and West Yellowstone, MT. Bozeman, Montana (population about 34,000), about 90 miles north of the park, also the largest airport in the region.
Philadelphia
kuai
Miami.
Honolulu, the capital of Hawaii is the closest US state capital to the equator. The closest U. S. territorial capital to the equator is Hagåtña, Guam.
naalehu, Hawaii
The closest Canadian city to the US border is Surrey, located in British Columbia. It is part of the Greater Vancouver area and shares a border with the US state of Washington.
Miami, Florida
Grand Forks, ND
Washington
McAllen, Texas