Chinatown - Manhattan, NY (Census tract 8) Population per square mile, 2010: 122,462.3

Brickell Key - Miami, FL (Census tract 6707) Population per square mile, 2010: 57,566.2

North Beach - San Francisco, CA (Census tract 106) Population per square mile, 2010: 53,868.7

Columbia Heights - Washington, DC (Census tract 36) Population per square mile, 2010: 35,668.8

Society Hill - Philadelphia, PA (Census tract 1001) Population per square mile, 2010: 29,388.7

Lakeview - Chicago, IL (Census tract 604) Population per square mile, 2010: 26,853.9

The Fan - Richmond, VA (Census tract 404) Population per square mile, 2010: 22,175.1

Flamingo/Lummus - Miami Beach, FL (Census tract 4304) Population per square mile, 2010: 18,446.3

French Quarter - Charleston, SC (Census tract 4) Population per square mile, 2010: 13,800.5

Jacksonville - The Space Inbetween (Census tract 1) Population per square mile, 2010: 13,442.8

Harbour Island - Tampa, FL (Census tract 5102) Population per square mile, 2010: 13,162.9

Midtown - Detroit, MI (Census tract 5203) Population per square mile, 2010: 11,700.7

Country Club Plaza - Kansas City, MO (Census tract 73) Population per square mile, 2010: 11,039.1

Old Louisville - Louisville, KY (Census tract 52) Population per square mile, 2010: 10,513.3

South Historic District - Savannah, GA (Census tract 9) Population per square mile, 2010: 10,278.7

First Ward - Charlotte, NC (Census tract 6) Population per square mile, 2010: 9,884.3

Jacksonville - Baymeadows (Census tract 15925) Population per square mile, 2010: 9,410.3

Montrose - Houston, TX (Census tract 410402) Population per square mile, 2010: 9,109.3

Ghent - Norfolk, VA (Census tract 37) Population per square mile, 2010: 8,934.8

Faubourg Marigny - New Orleans, LA (Census tract 18) Population per square mile, 2010: 7,847.4

Jacksonville - Avondale (Census tract 2101) Population per square mile, 2010: 7,057.7

Thornton Park - Orlando, FL (Census tract 102) Population per square mile, 2010: 6,869.2

Jacksonville - Jacksonville Beach (Census tract 14202) Population per square mile, 2010: 6,477.6

Jacksonville - Durkeeville (Census tract 2902) Population per square mile, 2010: 5,892.5

Channel District - Tampa, FL (Census tract 5301) Population per square mile, 2010: 5,685.1

East Nashville - Nashville, TN (Census tract 192) Population per square mile, 2010: 5,113.6

Jacksonville - Springfield (Census tract 11) Population per square mile, 2010: 4,159.5

Jacksonville - Brooklyn/Riverside (north of east of King St) (Census tract 171) Population per square mile, 2010: 3,967.3

Jacksonville - San Marco (Census tract 7) Population per square mile, 2010: 3,444,6

Source: US Census Bureau: http://projects.nytimes.com/census/2010/map