California was admitted to the Union as the 31st state on September 9, 1850. That year 27 original counties were created—but since then boundaries have been redrawn to form new ones, bringing the current total to 58. Mariposa County, one of the original 27 with an area of about 30,000 square miles, was by far the largest county by geographical measurement, covering 1/5 of the state. As established in 1850, Mariposa County included most of present-day Mono and Inyo counties; all of present-day Merced, Madera, Fresno, Kings, Tulare and Kern Counties; plus small portions of San Benito, Los Angeles, and San Bernardino Counties. The 1850 federal Census counted 4,379 residents, as compared to 3,530 in what then constituted the boundaries of Los Angeles County.