Yep, I've seen semi-flat bed trucks loaded with bees heading north on I-75. Last August, we were just west of Cody, Wyoming stopped at a road side view and a truck loaded with bees stopped.
It is my understanding that bees are taken to Alaska for pollination purposes but are destroyed at the end of the season.
Well, here in southeast Kentucky, practically all honey is a mix of various sources of nectar. White clover and sourwood might be the exceptions. About 7 years ago, there was a 75 acre tract of land sold. The new owner prepared about 50 acres of it for mixed hay (bluegrass and white clover). The fields were white with clover blooms the next spring/summer. My bees worked us to death putting the honey. Two years later, the owner leased the property for cattle grazing, thus clover was about a zero for honey production from those fields.
Back several years ago, when coal mining was big, they would sew clovers as part of the reclamation.