Here is an alternate flag of what could have been America if the Nazis have won WW II. If you are asking what Nazi America would be called as an alternate name, then I would say the "Nationalist-Socialist States of Amerika".
Government: Fascist Puppet State of Nazi Germany
Head of State: Fuhrer Adolf Hitler
Capital: New York City
Population: 312,828,000 (mostly Germans and English)
Established: June 15th, 1947
Ideology: Anti-Semitism, Anti-Liberalism, Fascism, Nationalist-Socialism, Anti-Capitalism, Anti-Communism, Anti-Homosexuality, Anti-Abortion, Nordic-Nationalism, Nazism, Anti-Anarchism