Union County
Union County (Arkansas)
 Union County (Florida)
 Union County (Georgia)
 Union County (Illinois)
 Union County (Indiana)
 Union County (Iowa)
 Union County (Kentucky)
 Union County (Mississippi)
 Union County (New Jersey)
 Union County (New Mexico)
 Union County (North Carolina)
 Union County (Ohio)
 Union County (Oregon)
 Union County (Pennsylvania)
 Union County (South Carolina)
 Union County (South Dakota)
 Union County (Tennessee)