143 articles
Oakland County, Michigan
Oakland County, Michigan: second-most-populous Michigan county (about 1.29 million) north of Detroit; county seat Pontiac; $127.3B GDP, AAA bond rating, 62 municipalities, Democratic-leaning after a Republican past.
Ocean County, New Jersey
Ocean County, New Jersey: county formed February 15, 1850 from Monmouth County lands south of the Manasquan River; county seat Toms River; 33 municipalities, 638 square miles, 45-mile Atlantic coast; population 637,229 (2020).
Okaloosa County
Okaloosa County, Florida: Panhandle county created 1915 from Santa Rosa and Walton counties, seat Crestview, named for a Choctaw 'black water' steamboat; home of Eglin AFB and Destin tourism.
Orange County, Florida
Orange County, Florida (FIPS 12095) is the central Florida county containing Orlando; created as Mosquito County in 1824 and renamed Orange in 1845, it had 1,429,908 residents in 2020, 13 municipalities, a charter government led by a countywide mayor, and a tourism-driven economy.
Orange County, New York
Orange County, New York: Hudson Valley county founded 1683, named for William III of Orange; only NY county bordering both Hudson and Delaware rivers; seat Goshen; population 401,310 (2020).
Osage County, Oklahoma
Osage County, Oklahoma: the state's largest county by area (2,303.8 sq mi), county seat Pawhuska, contiguous with the Osage Nation Reservation, created at 1907 statehood, known for Osage oil-boom history and the Tallgrass Prairie Preserve.
Ottawa County, Michigan, United States
Ottawa County, Michigan, a Lake Michigan county with county seat Grand Haven, organized 1837, named for the Ottawa tribe; population 308,459 (2025 estimate), one of Michigan's fastest-growing counties.
Palm Beach County, Florida
Palm Beach County, Florida: county established July 1, 1909 as Florida's 47th county, seat West Palm Beach; seven-member commission, 1.58 million residents (2025 est.), Florida's largest agricultural county.
Pasco County, Florida
Pasco County, Florida: Gulf-coast county created June 2, 1887 from Hernando County, named for Senator Samuel Pasco; seat Dade City; 561,891 residents in 2020, fast-growing Tampa Bay suburb.
Pierce County, Washington
Pierce County, Washington: county created December 22, 1852 from Thurston County, named for President Franklin Pierce; seat Tacoma; second most populous Washington county (921,130 in 2020), home to Mount Rainier, JBLM, and the Port of Tacoma.
Pima County, Arizona
Pima County, Arizona: second-most populous Arizona county, county seat Tucson, one of four original 1864 territorial counties. Covers 9,189 sq mi, population 1,043,433 (2020), FY2026/27 budget $1.809 billion.
Pinellas County, Florida
Pinellas County, Florida: a densely populated 280-square-mile peninsula between Tampa Bay and the Gulf of Mexico; county seat Clearwater, largest city St. Petersburg; became Florida's 48th county in 1912.
Polk County, Florida
Polk County, Florida: interior peninsula county established February 8, 1861, named for President James K. Polk, seat Bartow, largest city Lakeland; about 600 lakes, phosphate and citrus heritage, 874,790 residents in 2025.
Porter County
Porter County, Indiana: county in northwestern Indiana with county seat Valparaiso, established January 28, 1836 and named for Commodore David Porter; home to Indiana Dunes National Park and State Park; population 173,215 (2020).
Prince George's County, Maryland
Prince George's County, Maryland: a Washington, D.C.-suburban county erected from Calvert and Charles counties in the 1690s, named for Prince George of Denmark; seat Upper Marlboro; 967,201 residents (2020), 60.7% Black, charter government since 1970.
Prince William County, Virginia
Prince William County, Virginia: Northern Virginia county formed 1731 from Stafford and King George counties, named for King George II's son; second-largest Virginia county, seat Manassas, population about 503,000 in 2025, major data center hub.
Pulaski County, Arkansas, United States
Pulaski County, Arkansas: most populous Arkansas county (404,611 est. 2025), county seat Little Rock, state capital; established December 15, 1818, named for Casimir Pulaski; distinct from Pulaski County, Missouri.
Rapides Parish
Rapides Parish (Paroisse des Rapides), central Louisiana parish with seat Alexandria; created 1807, named for Red River rapids; 130,023 residents (2020), second-largest parish by land area.
Rensselaer County
Rensselaer County, New York: Capital Region county founded 1791 from Albany County, county seat Troy, area 665 sq mi, population 161,130 (2020), 19-member legislature, Tech Valley economy.
Richmond County, New York, United States
Richmond County, New York, coextensive with the Staten Island borough; one of New York's ten original counties, established November 1, 1683, named for the Duke of Richmond; 495,747 residents in 2020.
Riverside County, California
Riverside County, California: county formed May 9, 1893 from San Bernardino and San Diego counties, seat at Riverside city. Fourth-largest California county, about 2.5 million residents, logistics- and tourism-driven Inland Empire economy.
Rockland County, New York
Rockland County, New York: county founded February 23, 1798 from Orange County; county seat New City; smallest New York county outside NYC with 338,329 residents (2020), largest per-capita Jewish population, and a three-source water supply.
Sacramento County, California
Sacramento County, California: a 994-square-mile Central Valley county founded 1850, seat of California state government, seven incorporated cities, population about 1.6 million.
Saint Charles County
Saint Charles County, Missouri: county in the St. Louis metro area, organized October 1, 1812 as one of five original Missouri counties, named for St. Charles Borromeo; county seat St. Charles; 2025 population about 426,499, 3rd of 115 Missouri counties.
San Bernardino County, California
San Bernardino County is a county in Southern California, created from Los Angeles County in 1853. It is the largest US county by area and had 2,181,654 residents in 2020.
San Diego County, California
San Diego County, California: southwesternmost California county on the Mexico border, established 1850, second most populous of 58 counties, 3.28 million residents, $8.63 billion FY 2025-26 budget, $266.9 billion regional economy.
San Joaquin County, California
San Joaquin County, California: Central Valley county established 1850, county seat Stockton, eight cities, 823,815 residents (2025 est.), $3.15 billion agriculture, Port of Stockton, governed by a five-member Board of Supervisors.
San Luis Obispo County, California
San Luis Obispo County is a Central Coast California county, one of the original 27 counties (1850), seat at San Luis Obispo, population 282,424 (2020), 3,300 square miles, 100 miles of coastline.
Sangamon County
Sangamon County, Illinois: central Illinois county established January 30, 1821 from Madison and Bond counties, county seat Springfield (state capital), named for the Sangamon River; population about 194,000.
Santa Barbara County, California
Santa Barbara County, California: coastal county, county seat Santa Barbara, one of the original 27 counties created February 18, 1850, named for Mission Santa Barbara (1786); 2020 population 448,229.