This story takes place in 1875 on until about 1878, it revolves around two famous ex Texas Rangers. The Rangers Captain Gus and Captain Woodrow Call run a boarding stable named the Hat Creek Cattle Company and Livery Emporium. This stable is located in a dust bowl town in Texas called Lonesome Dove. The two men are getting into their later years in life and decide to take one last journey together. This journey involves them driving cattle north out of Texas and to Montana. It is a journey in self discovery as along the way they loose people who were employees and friends, the aging men learn about themselves coming to important realizations. This cattle driving takes the guys through Oklahoma, Kansas, and Nebraska. It sees the cattle drivers meet new people, some good and some bad. It is in these meetings that they find out what their own strengths and weaknesses are, they fight for their lives battling storms, Native Americans, and US Calvary. In the end, however, Gus, who had been shot by arrows, succumbs to his injuries and dies. Call then returns to the town of Lonesome Dove to bury Gus.
Because the first book in the series, Dead Man's Walk,takes place in 1841, when Gus and Call were young Texas Rangers, it can be estimated that Lonesome Dove takes place 20-30 years later, probably in the late 1860s-early 1870s.
Lonesome Dove most likely took place in late summer 1876 as Little Bighorn was June 25th 1876, but it could be early spring 1877 as springtime is mentioned as the crew starts branding cattle. Red cloud was safely housed on a reservation by early 1878.That should narrow the time frame from July 1876 to January 1878!
Lonesome Dove takes place in the late 1800's. The closest we can get to specifics is that it takes place after 1876, as Gus and Woodrow discuss Custer's last stand. It takes place before 1909, as the Army men who try to take Dish's horse mention that they are tracking Red Cloud, who died in 1909.