During the 1930s and the Great Depression, when Mathews was still living in his cabin, he was very politically active within the Osage Nation. As the people took advantage of the Indian Reorganization Act of 1934 and the Oklahoma Indian Welfare Act, Mathews helped the Osage Nation restore its self-government. He was elected to the Tribal Council, serving from 1934 to 1942. He helped found the Osage Tribal Museum, which opened in 1938 in Pawhuska, and donated numerous artifacts to it.