James “Jim” Masterson was born in Quebec on September 16, 1855, and moved with his family to Wichita, Kansas, in 1871. After hunting buffalo with his brothers, he opened a saloon in Dodge City, Kansas. A year later, his brother Ed, who was serving as the Dodge City Marshal, was killed in the line of duty. Jim became the Assistant Marshal in Dodge City, Kansas, in June 1878. While working for Marshal Charlie Bassett, Masterson also worked with Wyatt Earp, who was a Deputy Marshal.
In November 1879, he was promoted to Marshal when Bassett exceeded the terms he could serve. When a new mayor was elected in Dodge, Jim lost his job. Ten days later, he shot a man named Al Updegraff in a gunfight and was ordered out of Dodge City. He then moved to Trinidad, Colorado, where he served as a deputy and constable. By 1885, he had moved again to Raton, New Mexico, where he was appointed undersheriff of Colfax County. Moving again, he finally settled in Guthrie, Oklahoma, where he became the Logan County sheriff. In 1893, he became a U.S. Deputy Marshal and was involved in the Ingalls, Oklahoma shootout with the Doolin Gang. Masterson died of consumption on March 31, 1895.