I thought bumblebees are everywhere except maybe the desert?
Bombus sonorus -- the Sonoran Bumblebee -- is a common North American desert species.
To answer your question every critter has it's range. Even you do. Visited Antarctica recently? Or Mars?
If you were a bumblebee you'd have a range of about a quarter of a kilometer from your nest. In rare instances you might go as far as 800m distant. And therein you can see why climate change poses an adaptation challenge to bumblebees.
Bumblebee colonies die every winter. The old queen perishes and the new queens hibernate until the spring then disperse to a new nest site. So you can see that the species can only relocate northward at a fraction of a kilometer per year -- although it may have better luck moving vertically -- to higher altitudes where a convenient mountain is handy.
Species that adapt well to climate change either have individuals with large ranges, or they hitch a ride on critters that travel long distance. For example mosquito species have lifetime ranges on the order of 2-3 km, but the Asian Tiger Mosquito (Aedes albopictus), which breeds in small containers of water, usually spends its life within 100m or so of where it hatches. The Tiger Mosquito species was introduced to the US at Houston in 1985 and fifteen years later it was found all over the United States. How is this possible if an individual lives its entire life within a 100m radius of its hatching place? I went to a presentation at CDC Fort Collins where their arthropod borne disease doyen plotted out the spread of Ae albopictus and showed it followed the route of the US Interstate Highway system. Eggs and pregnant individuals hitched a ride. That's because cars and trucks provide things that mosquitoes are attracted to: people to bite and tiny pools of water trapped in spare tires or crevices of the machine for egg-laying. Note that Ae albopictus larvae are known to arrive in the US in a shipments of that "lucky bamboo" you can buy in Chinatown; those stalks hold maybe 20-30 ml of water. It takes a "container" with only a tablespoon or two of water to transport viable larvae.
Now back to bumblebees. Because bumblebee colonies are small (typically 50 individuals to 50,000 for honeybees) and temporary, bumblebees don't stockpile honey. So unlike honeybees humans have no reason to transport them deliberately. Likewise cars and trucks aren't attractive to bumblebees so it's rare that a new queen will get an accidental ride north with a human. So bumblebees are poorly adapted to a rapidly changing climate.