James Bryan Mason was born in Superior, Wisconsin on September 30, 1940. At the age of one, he and his family moved to Missouri where they took up farming on land near his mother's hometown. Living in rural Missouri, Mason grew up around the traditional farming techniques soon to be overtaken by the intensive farming practices he would write about in Animal Factories. Eventually, Mason's family gave up farming. His father became an inspector for a local milk processing plant and his mother became a teacher in the local public school system. When Mason finished high school, his parents moved to Florida.
Mason started college at the University of Washington in St. Louis. He spent two years there in the pre-med track before transferring to the University of Florida to complete his third year. Dissatisfied with his studies, Mason dropped out of college and spent the next two years traveling in New York and New England before being drafted into the U. S. Army. When he completed his military service, Mason returned to college at the University of Missouri where he finished his undergraduate degree and went on to earn his law degree. In 1969, Mason moved to Bridgeport, Connecticut to take a job as a staff attorney with a legal services project. He started his own law practice in Bridgeport in 1973, while devoting some of his free time to social and environmental activism.
In 1974, Friends of Animals President Alice Herrington introduced Mason to Peter Singer, then a visiting professor of philosophy at New York University. At the time, Singer was working on Animal Liberation, a book that was shortly to become a seminal work in the animal rights movement. Mason helped arrange for Singer to visit factory farming facilities in New York and Connecticut. Although Singer touched upon factory farming in Animal Liberation, both Mason and Singer thought the subject merited further exploration.
By 1975, when Mason and Singer began seriously discussing the possibility of collaborating on a book-length treatment of factory farming, Singer had returned to his native Australia to take a teaching position at La Trobe University in Victoria. Because of the constraints imposed by distance, Singer agreed to advise Mason on the organization and content of the book, while Mason agreed to do the bulk of the research. With little journalism or writing experience, Mason was eager to have the input of an established author in the field. Singer was willing to offer editorial advice, but refused any share of the profits from the sale of the book.
Mason began his research on factory farming by versing himself in the professional literature of agribusiness. He subscribed to farming magazines and requested information from agricultural schools and government agencies. To complement this course of study, Mason traveled around the U. S. and Canada visiting intensive farming facilities and agricultural research centers. Such extensive field work afforded Mason and Joseph Keller, the freelance photographer who traveled with him on some occasions, the opportunity to photograph the practices of the factory farming industry in action.
Published in Animal Factories, these photographs would provide the most hard-hitting evidence of factory farming's impact on animal welfare, human health and the rural way of life.
After much correspondence with Peter Singer, Mason finally settled upon a desired organization and format for his research. He assembled a proposal and manuscript that emphasized the photographic content of the book. Through his agent, Jennifer Gerard Maric, Mason and his collaborators secured a contract with Crown Publishers. Animal Factories was first published in 1980 and was reissued as a revised edition in 1990.