California was admitted to the Union as the 31st state on September 9, 1850. That year 27 original counties were created—Mariposa and San Diego Counties being the largest in acreage—but over time boundaries were redrawn to form new counties, bringing the total to 58. In 1850, Mariposa County, with an area of about 30,000 square miles, covered 1/5 of the state, since subdivided into Tulare, Mono, Merced, Madera, Fresno, Kings, and Kern Counties. The original San Diego County included the areas that today make up San Diego, Imperial, Riverside, San Bernardino, and half of Inyo Counties. Today, Los Angeles County is immensely populated. In 1850 Los Angeles County–which included portions of today’s Orange, Riverside, and San Bernardino Counties—had 3,530 residents.