The Union City micropolitan statistical area, as defined by the United States Census Bureau, is an area consisting of Obion County, Tennessee, anchored by the city of Union City, Tennessee.

As of the 2000 census, there were 40,202 people, 16,419 households, and 11,511 families residing within the μSA.

[1] The racial makeup of the μSA was 85.64% White, 12.42% African American, 0.13% Native American, 0.21% Asian, 0.04% Pacific Islander, 0.80% from other races, and 0.76% from two or more races.

Males had a median income of $29,682 versus $19,791 for females.

The Martin–Union City combined statistical area is made up of two counties in northwest Tennessee.