Which is city is the county seat of a county with a standard abbreviation of SU?
Sumner County, Kansas Sumner County (standard abbreviation: SU) is a county located in the U.S. state of Kansas. As of the 2010 census, the population was 24,132. Its county seat is Wellington.
Skagit County, Washington Skagit County is a county in the U.S. state of Washington. As of the 2010 census, the population was 116,901. The county seat and largest city is Mount Vernon. The county was formed in 1883 from Whatcom County and is named for the Skagit Indian tribe, which has been indigenous to the area prior to European-American settlement.