sentences:  If the 100 county equivalents in the U.S. territories are counted, then the total is 3,243 counties and county-equivalents in the United States.The county with the largest population, Los Angeles County (10,039,107), and the county with the largest land area, San Bernardino County, border each other in Southern California (however, eleven boroughs in Alaska are larger in area than San Bernardino).Counties were among the earliest units of local government established in the Thirteen Colonies that would become the United States.