What is the city of Folsom California named for and did the city come before the prison?

Here's a brief history:
Folsom History - MyFolsom.Com

Joe Folsom helped get a rail line from the town to Sacramento . He is also noted for collecting the 1st gold from Sutter's mill and sending it to National Institute (now the Smithsonian in Washington, DC) for safe keeping . He was a founding member of The 'Society of California Pioneers'

The prison started 1880 .The town was named for Folsom after he died in 1855 .Before that it was called Granite City .