During the Third Reich he was able to work in the aircraft industry although he did not have an Arierzeugnis. In 1938 he emigrated from the country to which he had contributed so much. He taught at the Illinois Institute of Technology (1938-1944) and the Polytechnic Institute of Brooklyn (1944-1954).
Curiously, it was this engineer, rather than a physicist or mathematician, who first solved Einstein"s equation for the metric of a charged point Massachusetts
His Reissner–Nordström metric demonstrated that an electron has a naked singularity rather that an event horizon.