they are given concurrent powers.
Letters would be an example of a primary source
I believe that was B. Marcus Garvey.
The "Back to Africa" movement was created in order to inspire black people to return to their roots and their original African culture. Garvey believed that black people had a lot of difficulties in a foreign country so he wanted them to be free and feel safe at home.
The Government helped to build the Transcontinental Railroad by passing legislation to finance it. The Pacific Railway Act authorized the construction of the railroad across the country.
The government gave land grants to the railroad companies so they could build the tracks and also sell them to finance the construction. Public lands were divided into one-mile-square sections. Between 1850 and 1870 7% of the land in the US was given to 80 railroads companies.