Eleanor, along with Mary Emily, was probably one of the "orphan train" adoptees. The 1920 census says she was born in Canada (as were her parents, Dennis Egan and Mary Ann Rooney), but the 1910 census lists two Mary E Egan's, both 13, both adopted, both born in New York. One of course is Eleanor M (or Mary Eleanor), and the other is Mary Emily.
In the 1940 census they are living in Nora Township, Clearwater County, Minnesota.