The opera is inspired by the 1851/1852 letters of Louise Clappe, who lived for a year and a half in the mining settlement of Rich Bar (now Diamondville, California) during the California Gold Rush. Clappe published the letters under the pen name Dame Shirley.[3][4] The libretto is also sourced from other literature of the period, including newspaper articles and the writings of Mark Twain. Adams wrote, "To be able to set to music the authentic voices of these people, whether from their letters or their songs or from newspaper accounts from their time, is a great privilege for me." Sellars, who also directed the opera, conceived the libretto while doing research for a production of Giacomo Puccini's 1910 opera La fanciulla del West (based on David Belasco's 1905 play The Girl of the Golden West), which also deals with the gold rush period. According to Sellars, "These true stories of the Forty-Niners are overwhelming in their heroism, passion and cruelty, telling tales of racial conflicts, colorful and humorous exploits, political strife and struggles to build anew a life and to decide what it would mean to be American."[5]
In January 2023 two live performances of the opera, performed at Walt Disney Concert Hall and conducted by the composer were recorded for Nonesuch Records, and were released in April 2024.