Born in Ohio in 1812, John Weller was admitted to the Ohio Bar in 1832, and opened a private practice in Butler County. He was the prosecuting attorney of Butler County from 1833 until 1836, and served as a Lt. Colonel, 1st Regiment of Ohio Volunteers, during the Mexican-American War. John Weller was a U.S. Congressman from Ohio 1839-1845, but he lost a bitterly fought campaign for governor of that state in 1848. During 1849-1850 Weller was a member of the commission to establish the boundary between California and the Republic of Mexico, but was removed from this position following a scandal he was involved in. He moved to San Francisco in 1850, where he was elected to the United States Senate for the 1852–1857 term. As governor of California from 1858 to 1860, Weller intended to make California an independent republic if the North and South divided over slavery. In 1859, he signed legislation that would allow the counties of Los Angeles, San Bernardino, San Diego, Santa Barbara, San Luis Obispo and Tulare to separate from California and form the territory of Colorado. After leaving office on January 9, 1860, he was appointed the United States Minister to Mexico until he was recalled from that position in 1861. John Weller moved to New Orleans in 1867, practicing law there until his death in 1875.