Lathrap left California in 1959, taking a post at the Department of Anthropology at the University of Illinois at Champaign-Urbana, where he significantly influenced the department's archaeological direction. He worked in South American archaeology, which focused on the Amazon and Peru.
Lathrap departed California in 1959, assuming a position at the Department of Anthropology at the University of Illinois at Champaign-Urbana, where he substantially shaped the department's archaeological course. He specialized in South American archaeology, concentrating on the Amazon and Peru.