Unlike virtually every other city in the United States other than St. Louis, Baltimore City is a stand-alone city. It is not a part of a county, but it is bordered by counties that in many ways are bigger than big cities. Baltimore, Anne Arundel, Harford and Howard Counties have around 2 million residents combined and a land mass of close to 2,000 square miles. Baltimore City has about 630,000 residents and covers 90 square miles. What's more, the counties' chief elected officials, county executives, have enormous powers that are as great or greater than Baltimore's mayor.