Animated map shows the 143 counties where half of the US lives

According to 2015 census estimates, half of the US population lives in these 143 counties (ranked by population): 

Los Angeles County, California
Cook County, Illinois
Harris County, Texas
Maricopa County, Arizona
San Diego County, California
Orange County, California
Miami-Dade County, Florida
Kings County, New York
Dallas County, Texas
Riverside County, California
Queens County, New York
San Bernardino County, California
King County, Washington
Clark County, Nevada
Tarrant County, Texas
Santa Clara County, California
Bexar County, Texas
Broward County, Florida
Wayne County, Michigan
New York County, New York
Alameda County, California
Middlesex County, Massachusetts
Philadelphia County, Pennsylvania
Suffolk County, New York
Sacramento County, California
Bronx County, New York
Palm Beach County, Florida
Nassau County, New York
Hillsborough County, Florida
Orange County, Florida
Cuyahoga County, Ohio
Franklin County, Ohio
Oakland County, Michigan
Allegheny County, Pennsylvania
Hennepin County, Minnesota
Travis County, Texas
Fairfax County, Virginia
Con tra Costa County, California
Salt Lake County, Utah
Montgomery County, Maryland
Mecklenburg County, North Carolina
Wake County, North Carolina
Fulton County, Georgia
Pima County, Arizona
St. Louis County, Missouri
Honolulu County, Hawaii
Westchester County, New York
Fresno County, California
Milwaukee County, Wisconsin
Pinellas County, Florida
Fairfield County, Connecticut
Marion County, Indiana
Bergen County, New Jersey
Shelby County, Tennessee
DuPage County, Illinois
Erie County, New York
Collin County, Texas
Duval County, Florida
Prince George's County, Maryland
Hartford County, Connecticut
Gwinnett County, Georgia
Kern County, California
Macomb County, Michigan
San Francisco County, California
New Haven County, Connecticut
Ventura County, California
Pierce County, Washington
Hidalgo County, Texas
Middlesex County, New Jersey
El Paso County, Texas
Baltimore County, Maryland
Montgomery County, Pennsylvania
Worcester County, Massachusetts
Hamilton County, Ohio
Essex County, New Jersey
Multnomah County, Oregon
Denton County, Texas
Suffolk County, Massachusetts
Oklahoma County, Oklahoma
Essex County, Massachusetts
Snohomish County, Washington
San Mateo County, California
Jefferson County, Kentucky
Monroe County, New York
Cobb County, Georgia
DeKalb County, Georgia
San Joaquin County, California
Fort Bend County, Texas
Lake County, Illinois
Lee County, Florida
Norfolk County, Massachusetts
Jackson County, Missouri
Will County, Illinois
Denver County, Colorado
Davidson County, Tennessee
Bernalillo County, New Mexico
Hudson County, New Jersey
El Paso County, Colorado
District of Columbia, District of Columbia
Jefferson County, Alabama
Polk County, Florida
Tulsa County, Oklahoma
Kent County, Michigan
Providence County, Rhode Island
Arapahoe County, Colorado
Monmouth County, New Jersey
Bucks County, Pennsylvania
Baltimore city, Maryland
Ocean County, New Jersey
Johnson County, Kansas
Utah County, Utah
Washington County, Oregon
Brevard County, Florida
Jefferson County, Colorado
Anne Arundel County, Maryland
Delaware County, Pennsylvania
New Castle County, Delaware
Bristol County, Massachusetts
Union County, New Jersey
Douglas County, Nebraska
Summit County, Ohio
Stanislaus County, California
Ramsey County, Minnesota
Montgomery County, Texas
Lancaster County, Pennsylvania
Montgomery County, Ohio
Kane County, Illinois
Dane County, Wisconsin
Volusia County, Florida
Guilford County, North Carolina
Chester County, Pennsylvania
Sedgwick County, Kansas
Camden County, New Jersey
Passaic County, New Jersey
Plymouth County, Massachusetts
Williamson County, Texas
Sonoma County, California
Morris County, New Jersey
Pasco County, Florida
Greenville County, South Carolina
Adams County, Colorado
Spokane County, Washington
Lake County, Indiana