Ramsey County is a county located in the U.S. State of Minnesota. As of 2000, the population is 511,035. Its county seat is St. Paul. According to the U.S. Census Bureau, the county has a total area of 441 km˛ (170 mi˛). 403 km˛ (156 mi˛) of it is land and 37 km˛ (14 mi˛) of it is water. As of the census of 2000, there are 511,035 people, 201,236 households, and 119,936 families residing in the county. The population density is 1,267/km˛ (3,281/mi˛). There are 206,448 housing units at an average density of 512/km˛ (1,325/mi˛).

Ramsey County is the first and only Minnesota County to be governed by Home Rule; state statutes govern all other counties. Cities and towns of Ramsey County include Arden Hills , Falcon Heights, Gem Lake, Lauderdale, Little Canada, Maplewood, Mounds View, New Brighton, North Oaks, North St. Paul, Roseville, Shoreview, St. Paul, Vadnais Heights, White Bear Lake, and White Bear Township.

Neighbouring counties of ramsey county include Washington County ,Dakota County, Hennepin County, and Anoka County.