A People's History of the United States is written with an extreme leftist slant. Howard Zinn is strongly biased against capitalism and towards a Marxist interpretation of society and history.
The book does not really try to be even-handed. Zinn is avowedly left-wing and his book is a polemic that is meant to try to convince the reader to accept a Marxist analysis of US history. In every chapter of the book, Zinn tries to show how elites have constantly been trying to maintain and solidify their dominant position in US society. He tries to rectify the dominance of the elites by exposing their actions and by trying to highlight actions taken by nonelites to resist the elite. In this way, there is a very strong leftist bias in this work.