Bumble bees are almost cosmopolitan. They are more abundant and represented by a larger number of species in the northern hemisphere, especially in temperate zones. They prefer relatively drier climates.
Originally they were absent only in Antarctica, Australia and New Zealand. But in the last century they were introduced in New Zealand to help with alfalfa pollination. Attempts to introduce them to Australia years ago failed. Nowadays, green house tomato growers are pressing for permission to import European bumble bees; but they face strong opposition from those who oppose the entry of alien species. Recently bumble bees became established in Tasmania, after making their way there, either illegally or accidentally. There is strong surveillance to prevent the species from entering the mainland, but occasionally a bumble bee queen makes its way there. Perhaps it is just a matter of time.
In North America there are approximately fifty species. Some can prosper in a wide range of habitats others are more limited. Some are found only in the West Coast, others in the East. There are northern and southern species, for instance the tricolored bumble bee is mostly a northern species, seldom found south of Pennsylvania. There is a species, the polar bumblebee or Bombus polaris, found within the Arctic Circle; it takes full advantage of the explosion of little flowers that occurs in such latitudes through a very brief period. In that short time it has to raise a family and complete its full life cycle. This species has only small colonies. Other bumble bees do well in arid regions or at fairly high elevations.
Bumble bees can be found in farms, in suburban gardens and even in cities. Anywhere that flowers bloom, it is likely that there are bumble bees. The most serious limitation to their existence in cities is the lack of appropriate nesting sites; however some hardy souls manage to prosper in the concrete jungle.
Sadly, there are signs that not everything is well with bumble bees populations. Despite our limited knowledge, there are some evidences of declines, maybe even extinctions, of some populations. In England, where bumble bees are better studied than in the United States, there is clear evidence of the loss of some populations of bumble bees. There are even two species that are believed extinct in Great Britain, although the same species are still represented in the continent.