Perkins sold over two million copies of her books and was Houghton Mifflin's most profitable author. Her final book, The Dutch Twins and Little Brother was published posthumously in 1938. She died in Pasadena, California of a heart attack from coronary thrombosis on March 18, 1937; she had recently moved there with her husband in an effort to restore her health. Perkins had two children: Eleanor Ellis, a writer, and Lawrence Bradford, an architect