The Last Way West — J.R. Roberts

A friend of Clint's, a longtime Wagonmaster, is about to lead his final train west from Independence, Missouri. But suddenly, while in a saloon with Clint, he dies of a heart attack. Clint pays to have the man buried, but before he leaves town the Wagon Train's Captain comes to him and asks him to take over as Master. Since wagon trains are all but extinct, Clint decides to accept the offer, on behalf of his dead friend's last train. He leads the train west, dealing with all the problems that this entails -- illness, injury, wagons breaking down, thieves, and the possibility of being killed.