What is going on here?
The gold rush reached its peak in 1852 when ~ $81 million was pulled that year. From then on the yearly amounts began to level out at ~ $45 million.
In 1852, Harriet Beecher Stowe published Uncle Tom's Cabin. She wrote this in response to the Fugitive Slave Act. It sold over 300,000 copies in its first years of publication.
In 1859, Oregon is admitted into the Union as the 33rd state. Giving the people another free state.