Biographies:
* The Launching of Modern American History (1948): A history of the period between 1815 and 1860, focusing on the emergence of modern American society.
* Herbert Hoover and the Great Depression (1962): A critical biography of the 31st President of the United States, exploring his policies and legacy.
* The Origins and Evolution of the United States Senate (1950): A detailed examination of the history and development of the U.S. Senate.
* Joseph Conrad: Giant in Exile (1962): A biographical study of the Polish-born novelist, focusing on his literary career and personal life.
* Andrew Carnegie (1970): A biography of the industrialist, philanthropist, and entrepreneur, exploring his rise to power and his role in shaping American society.
Other works:
* The Last Titan: A Life of Thomas Wolfe (1947): A biography of the American novelist Thomas Wolfe.
* The American Character (1963): A study of American culture and national identity.
* The World of the Late Renaissance (1969): A historical overview of the late Renaissance period, including its art, literature, and culture.
Leo Gurko's writing is characterized by its thorough research, insightful analysis, and engaging narrative style. He has been praised for his ability to bring complex historical figures and events to life for general readers.