John C. Fremont was one of most famous explorers of the American West and a towering figure in the history of California's 19th century gold rush. Among the second rank of explorers to follow Lewis & Clark into the American frontier, in the late 1830s and early 1840s he explored and surveyed much of the American west, in particular the Oregon Trail. He eventually settled in California and grew wealthy during the gold rush of 1848. Nationally famous as an explorer, soldier and politician, in 1850 Fremont became one of the state's first two senators. He was the Republican party's first ever candidate for president in 1856 and ran again in 1860, withdrawing that year in favor of Abraham Lincoln.

Extra credit: Fremont was the son-in-law of famous Missouri senator Thomas Hart Benton, having married Benton's daughter Jessie.