September 29, 1903, Nocona, Texas.
February 16, 1992, Los Angeles, California.
Forest Lawn Memorial Park, Los Angeles, California.
Harper grew up primarily in Oklahoma, where he had many influences, both religious and musical, that would shape his future. He grew up with two devoutly Christian friends who, over time, were partly the cause of him accepting the faith.
He was a natural guitar player and had an interest in traditional western country music, but also newer genres such as western jazz, leading him to learn to play the trumpet as well.
In his teens, he discontinued his work as a cattle hand and rancher to pursue journalism. He enrolled in the University of Oklahoma and, upon graduation, began work as a newspaper reporter. However, he always aspired to become a country musician.
Harper was a part of a concert band that became more and more successful, until they were invited to join an Oklahoma City radio station in 1924. From there, his career took off, and his music was in greater demand. In 1931 he joined a larger radio station in Des Moines, Iowa, found more success, and decided to head to Hollywood, California. However, he arrived at the end of the western jazz era and the start of the Great Depression, making it hard to find work. When World War II started, he joined the Coast Guard for three years.
After the war, he found success again in Hollywood as he began working with other big name artists of the time from both radio and cinema. During this time, he also worked the movie industry and starred in several films, including The Strawberry Roan.
In 1950, Harper attended a Hollywood Christian meeting and was fully converted. Christianity became the predominant influence in his life, and his songs began to reflect the change. He started combining his musical talents with his new passion for evangelism.
Some time after his conversion, he went on missionary expeditions to the South Pacific, New Zealand, Australia, the Philippines, Hong Kong, Japan, Europe, and Africa. He spent the rest of his life in evangelism.