Do you live in an allergenic city?
#1 this year is Wichita, KS.
I grew up in Augusta, GA, ranked number 27 on there based on the amount of allergic prescriptions and use of OTC allergy medicine. I'll tell you why: It's not just the pollen or the number of physicians, it's all the friggin industries in the area. Federal Paperboard and Proctor & Gamble are the worst causes, but the dog food plant was particularly offensive some days.
I often joke that I was allergic to Augusta, and it seems I wasn't kidding. Since I moved away I stopped taking Claritin regularly and only really need to worry about my nose running during allergy season (like ragweed season right now. Bleah.)