Steinbeck never allowed his personal life—that is to say, his romantic and family business—to seep into his fiction. In 1941 he divorced his first wife and moved to New York City with his new romantic interest Gwyndolyn Conger. The couple married in 1943 and had two sons, Steinbeck's only children, in 1944 and 1946. Within two years of their youngest son's birth they too were divorced, and in 1950 Steinbeck married Elaine Anderson Scott, his third and final wife. Steinbeck was an intensely private man, even after he became famous, and despised public scrutiny of his personal affairs.
Steinbeck wrote about personal experience in a different way. His interests stretched from marine biology to history, and he used the years after his Grapes of Wrath fame to explore other topics that intrigued him. In 1940 he spent six weeks in the Gulf of Mexico with his close friend, the marine biologist Ed Ricketts. The two men co-wrote a book about the expedition entitled Sea of Cortez. In the early years of World War II Steinbeck traveled to Europe and North Africa as a war correspondent for the New York Herald Tribune. He also wrote for film, earning a screen credit for Elia Kazan's Emiliano Zapata biopic "Viva Zapata!" and an Academy Award nomination for his work on the 1944 Alfred Hitchcock picture "Lifeboat." He also continued to publish novels set in Steinbeck Country, such as Cannery Row in 1945 and The Wayward Bus in 1947.
Steinbeck made his first trip to the Soviet Union in 1947 as a journalist, accompanied by the photographer Robert Capa. Even before the trip, the pro-worker sentiments of his novels had attracted government suspicion. He was under surveillance by the Federal Bureau of Investigation starting in the early 1940s, though apparently the bureau was not all that discreet. "Do you suppose you could ask Edgar's boys to stop stepping on my heels?" Steinbeck wrote to Attorney General Francis Biddle in 1942, referring to FBI director J. Edgar Hoover. "They think I am an enemy alien. It is getting tiresome." His trip to Russia confirmed many people's suspicions that Steinbeck was a socialist. But while Steinbeck's work and travels brought him into frequent contact with labor organizers, strikers, and communists, he was not a card-carrying member of the Communist Party, Socialist Party, or any other particular camp. Books such as In Dubious Battle showed workers being manipulated by labor organizers as well as by corporate farmers. Steinbeck was no revolutionary; in his later years, his friendship with President Lyndon B. Johnson and his largely pro-war reporting on Vietnam drew criticism from liberals and leftists.