Indianapolis is the capital of the U.S. state of Indiana and the county seat of Marion County Indiana. As of the 2010 United States Census the city's population is 829 718. It is Indiana's largest city and as of the 2010 U.S. Census is the 12th largest city in the U.S. the second largest city in the Midwest the second most populous state capital and the most populous state capital east of the Mississippi River.