Amidon (pronunciation: /æmɪdɒn/ am-i-don) is a city in Slope County, North Dakota in the United States. It is the county seat of Slope County. The population was 20 at the 2010 census, making it the second least populous county seat in the United States, behind only Mentone, Texas (population 19), the county seat of Loving County.
Amidon was founded in 1910 at the anticipated terminus of a Milwaukee Road branch line that diverged from the railroad's Pacific Extension in McLaughlin, South Dakota. The line was ultimately never built farther west of New England, North Dakota, making Amidon one of the few surviving North Dakota cities to have never been served by a rail line.
Located on US 85 about 31 miles (50 km) north of Bowman, North Dakota, it is the closest city to White Butte.