LeRoy Reuben Hafen was born 8 December 1893 in a Mormon town known as Bunkerville, Nevada. The twelve-pound baby boy was born to a polygamist father, John George Hafen and his second wife Mary Ann Stucki Hafen. Growing up in an experimental communal living with thirty-six households, LeRoy's character was shaped by two dominant forces: the Mormon Church and the Virgin River. As a member of the Church of Jesus Christ of Latter-day Saints, LeRoy developed the virtues of hard work, thrift, and the value of cooperation. From the periodically flooding Virgin River, LeRoy learned how to press forward in the face of adversity. Much of his youth was spent helping take care of his family's farm, and working at a vineyard in Mesquite (Nevada) during the summer. He also developed a talent for playing the violin, which he played for many church functions.

To pursue his education, LeRoy attended high school in Cedar City (Utah) for two years. Then he attended St. George Stake Academy located in St. George (Utah) for two more years, graduating in 1913. It was also in St. George that Hafen met Ann Woodbury, the daughter of John Taylor Woodbury and Mary Elisabeth Evans Woodbury. It was love at first sight and the two were married 3 September 1915 in the St. George Temple. They had two children, daughter Norma born 25 June 1916 and son Karl LeRoy born 3 September 1919. Norma later died in 1935 at the age of 19 due to a serious illness. To continue his education, LeRoy received his bachelor degree at Brigham Young University where he also spent three years on the collegiate debate team and was the manager of debating. He taught school at Bunkerville (Nevada) for a year, then became principal of Virgin Valley High School. Hafen also completed his Master's degree in history at the University of Utah, with a thesis on the Mormon Hand Cart Migration. In 1920, after saving some money, LeRoy moved his family to Berkeley (California) where he became a graduate student at the University of California. In 1924, he received his Ph.D. in history for his dissertation on the Overland Mail, 1849-1869. While furthering his education, he taught a year in a private school. To put himself through college, LeRoy worked during the school year and during the summer at cantaloupe farms in Overton (Nevada), and a ranch near Las Vegas (Nevada).

On 1 July 1924, LeRoy took a job as the State Historian and Director of the State Museum at Denver (Colorado). Here he put in thirty years of service. Some of his responsibilities included writing, research, and editing the , preparing and erecting historical markers, and acquiring and arranging exhibits for the Colorado State Museum. During the Great Depression, LeRoy supervised forty to fifty people in the WPA, one of the New Deal's programs to increase employment. The project was a first for the U.S., in which he led the group in gathering and filing historical data for the State Historical Society of Colorado and creating dioramas illustrating the history of the Rocky Mountain Fur Trade. He also wrote and directed the first documentary color movie for the history of any state. Since this job paid less that living wage, he taught Colorado, Western and American history at the University of Denver, to supplement his income.

During his thirty years as Colorado State Historian, LeRoy published more than fifty articles, and edited and wrote several more historical works. His works primarily covered the history of the west. He edited a five-volume history of Colorado, as well as wrote a single volume history of Colorado. Hafen wrote a biography for mountain man, Thomas Fitzpatrick with several other authors to produce books such as , a book on Fort Laramie, and with his wife Ann, a Colorado history book to be used in public schools.

In 1947, he had the opportunity to lecture at the University of Glasgow in Scotland. This gave LeRoy and his wife the opportunity to visit the land where their parents were born. From 1949-1950, LeRoy also received a fellowship for a year to the Huntington Library.

In 1954, LeRoy accepted a job as a professor of history at Brigham Young University (Provo, Utah). He spent seventeen years teaching Early American History and Latin American History, as well as a Western American History and Western History seminar. Between 1954-1960, the Hafens donated their collection of over three thousand books and two thousand pamphlets to Brigham Young University. Combining their efforts, LeRoy and Ann, who had a talent for poetry, completed a fifteen volume series of documentary material known as . They also wrote an autobiography entitled . It was published in 1973, three short years after Ann W. Hafen had passed away due to cancer. Before her death, Ann had wished that LeRoy might marry one of her widowed sisters. So, after he retired from teaching in 1971, he married Ann's sister Mary.

Dr. LeRoy R. Hafen has received numerous awards and recognitions, which include: Jew Oratorical Medal in 1916, since 1935, Litt. D. Degree at the University of Colorado in 1935, the Rockefeller Fellowship at the Huntington Library, plus many service awards. Hafen died in 1985 at the age of ninety-one. *Information taken from , LeRoy R. Hafen Biography by Carter, and the LeRoy R. Hafen Biography from Brigham Young University.