If we went back in time almost two hundred years and found a map, we're not sure if Lonesome Dove would be on it. It's deep in the heart of Texas. We think. We're not sure where the heart of Texas is, but Lonesome Dove is deep in the southern part of Texas, on the border with Mexico, near the Rio Grande.
Needless to say, it's hot. Lonesome Dove is one of those places where it's hot even in the shade, but that one less degree in the shade is a blessing.
"Evening took a long time getting to Lonesome Dove, but when it came it was a comfort." (1.3)
People in Lonesome Dove seem to move from shady spot to shady spot. Some people like that way of life. Some don't. The ones who don't are the ones who leave.
Okay, so it's not the simple. Gus is torn. He's the type of guy who loves to sit in the shade and drink—but he also likes a little bit of action, which is no longer happening in Lonesome Dove. It used to be a happening place, but the bandits and Native Americans have all moved elsewhere or are dead. Now, "the one street was still and empty, with only one horse twitching its tail in front of the Pumphreys' store" (23.25). Next time you think there's nothing to do in your hometown, think of Lonesome Dove.
Gus says, "It's funny leaving a place, ain't it? […] You never do know when you'll get back" (23.107). This is some prime foreshadowing, because the last thing Gus probably expects is to die and have his body returned to Lonesome Dove—but that's totally what happens.
There's also a metaphorical aspect to the title. A dove is a bird of peace, and, despite a life of fighting bandits, many of the former Texas Rangers in the book are now peaceful, lonely men. Everyone is lonesome in his or her own way. Clara is raising her family alone. Lorena is trying to make a life for herself. Call is a lone wolf. Newt has no father. Almost every character can be a lowercase lonesome dove in his or her own way.