Has moving to different elevations helped your hives?

Hi,
So I'm wondering if what I've experienced has happened to anyone else.  I grew up in Raleigh, NC which is in the piedmont region of North Carolina.  During my freshman year of high school I began getting terrible hives.  Nothing I took really seemed to get rid of them, and the allergists (I tried a few) never could tell what was causing them.  This lasted on and off for the rest of high school.  After high school, I went to college in Boone, NC which is in the Appalachian mountians.  My hives immediately improved.  I had one or two minor episodes during my freshman year, each of which went away as soon as I started taking my pills (atarax and zantac).  I didn't have any hives the next three years in the NC mountains.  I then spent one year in Charleston, SC by the beach and still had no hives.  I moved back to the Raleigh area and quickly began getting hives again.  Six months later I moved out to Montana and my hives immediately went away.  I've been here for 3 months with no sings of hives.  

I'm curious as to whether changing locations has helped get rid of hives for anyone else.  I'm also wondering if there is anything about the higher or low elevations that may have helped.  I also wonder if the dry air in MT or the large amounts of rain at the beach or in the Appalachian mountains may have helped.