[2] In 1915 Whittemore organized state branches of the Congressional Union in California, Michigan, and Ohio.

Her sister-in-law, Marjorie Miller Whittemore, became head of the Michigan branch of the subsequent National Woman's Party.

[2] Through the NWP Whittemore was involved in advocating for federal suffrage in the western states of Washington,[3] Oregon,[4] and Idaho.

In 1917 she was arrested and spent three days in jail along with several other suffragists for picketing the Wilson administration in front of the White House.

[6] In 1922, after women had won the right to vote, Whittemore continued her activism, specifically she and Mabel Vernon drove from Indiana to California, supporting women candidates running in the 1924 elections.