Texas Rangers

Mike Cox, of True West, has a book about the history of the Rangers:

Third-generation journalist Mike Cox was born in Amarillo, Texas and raised in Austin, Texas. After twenty years of working for newspapers, he went to work for the Texas Department of Public Safety for fifteen years, and then the state highway department and the Texas Parks and Wildlife Department, before retiring in 2015. A member of the Texas Institute of Letters, Cox has written 28 nonfiction books and hundreds of articles, including his highly rated two-volume Ranger history, Wearing the Cinco Peso: The Texas Rangers 1821-1900 and Time of the Rangers: Texas Rangers 1900 to Present. He has three more books under contract and is the editor of the Wild West History Association Journal. He now lives in the Hill Country community of Wimberley, Texas.
Cox says the narrowing of a list of the best Ranger books down to just five is, like the old “one Ranger, one riot" legend, easy to say, hard to do. Here are his top six:

Six Years with the Texas Rangers, 1875-1881 (James B. Gillett, Andesite Press): The best nineteenth-century Ranger memoir is James B. Gillett’s. First published in 1921, it remains in print for good reason. It is highly readable and full of insight into the life and duties of the Frontier Battalion-era Ranger.
Trails and Trials of a Texas Ranger (W.W. Sterling, University of Oklahoma Press): The best early twentieth-century memoir is Bill Sterling’s. Privately published in 1957 shortly before the old Ranger’s death, this book was out of print for a while, but the University of Oklahoma Press brought it back to life in 1969, and it remains in print today.
One Ranger: A Memoir (Joaquin Jackson, University of Texas Press): The best late-twentieth-century memoir, a fine inside look at the modern-day Texas Ranger’s life is the late Ranger Joaquin Jackson’s. Published in 2005, it remains that publisher’s top-selling book to date. Texas author David Marion Wilkinson worked with Jackson in writing the book.
Yours to Command: The Life and Legend of Texas Ranger Captain Bill McDonald (Harold J. Weiss, University of North Texas Press) and Texas Ranger John B. Jones (Rick Miller, University of North Texas Press): The best nineteenth-century ranger biographies are a draw. Captain Bill, as he was known, contributed heavily to the Ranger legend and Weiss does a great job sorting out truth and fiction in this work. Jones served as the first major of the Frontier Battalion when it was created in 1874, and rose to the position of state adjutant general before his early death in 1881.
Texas Ranger: The Epic Life of Frank Hamer, the Man Who Killed Bonnie and Clyde (John Boessenecker, Thomas Dunne Books): Boessenecker’s new book is the best twentieth-century Ranger biography. Hamer served as a Ranger from 1906 through the early 1930s. Bossenecker successfully argues that the publicity Hamer garnered for the Rangers in the killing of Bonnie Parker and Clyde Barrow helped save the Rangers from the legislative axe.

Rico says that Cox always does a good job; Rico owns most of these books...