In 1970, he taught for a year at
Franconia College. In 1971, Wallace accepted a teaching position at
John Jay College of Criminal Justice. In the early 1970s, Wallace began working with other historians of his generation who were "broadening the scope of American history by adding the voices of those previously excluded, such as women, blacks and the working class." In 1973, Wallace helped launch, and for the next ten years directed, the Radical History Forum. He also participated in transforming the ''Radical Historians' Newsletter
, started in 1973, into the Radical History Review'', by 1975, and then served as its editorial coordinator. During the 1980s, Wallace wrote essays about the ways history gets presented – or misrepresented – to the general public, outside of schools and universities. In 1996, these pieces were collected in a book called
Mickey Mouse History and Other Essays on American Memory. In 1998, he co-authored (with
Edwin G. Burrows)
Gotham: A History of New York City to 1898, which in 1999 won the
Pulitzer Prize in History. In 2000, Wallace founded the Gotham Center for New York City History, a non-profit organization. It is part of the Graduate Center of the City University of New York. The successor volume,
Greater Gotham: A History of New York City from 1898 to 1919, was published on October 2, 2017. The third volume,
Gotham at War: A History of New York City from 1933 to 1945 was published on October 1, 2025. ==Personal life==