Like elephants in a circus parade, lines of cumbersome tractor/trailer rigs hauling farm equipment make their way from deep in the heart of Texas, across the plains and into Canada, harvesting the wheat fields as they go. These caravans set out to the southernmost fields in late spring and work their way north - following the summer heat as it tracks northward and ripens the wheat - and return back home in the fall.
These modern nomads travel with their own living quarters, so RV parks and lots that usually sit empty become villages for a few weeks, then everything returns to it's place on the trucks and the caravan heads to the next stop to repeat the entire process. Farmers will re-hire the same crew each year, if they're good at what they do, so some of the wanderers are familiar faces each summer.
Not all farmers hire crews to cut their wheat. The ones who do say it is because hiring it done is more cost efficient than purchasing and maintaining combines and trucks and hiring help to run them. Custom crews can definitely be more time efficient, putting three, four or more combines into a field at once, and since time is of the essence when you're battling Mother Nature, this can be a huge benefit. If you asked those who cut their own crop, they would likely tell you that custom cutters are too expensive and they can do it more reasonably on their own. Only a few will admit that, regardless of cost, they just enjoy the hands-on experience of harvest.