There are 30 US Post Offices in Polk County serving a total of 369,644 residents equating to 12,321 residents per post office. It's estimated that approximately 589,993 packages are handled across the 30 county post offices annually. Polk County is located in the State of Florida. The county population was 602,095, as of the 2010 census. Its county seat is Bartow, and its largest city is Lakeland. Polk County is part of the greater Tampa Bay Area. Polk County comprises the Lakeland-Winter Haven Metropolitan Statistical Area. This MSA is the 87th most populous metropolitan statistical area and the 89th most populous primary statistical area of the United States as of July 1, 2012. The center of population of Florida is located in Polk County, near the city of Lake Wales. Polk County is home to one public university, one state college, and four private universities. One Fortune 500 company \u2013 Publix Super Markets \u2014 has headquarters in the county."