I too think Regional would be best. This would allow us to read information that would be most appropriate for our operations. If you are on the border of your region you could easily visit your neighbor region for info as well.
Region I: New England - ME, NH, VT, CT, RI, NY, PA, MA
Region II: Mid Atlantic - DE, MD, VA, NC, NJ
Region III: Southeast - SC, GA, FL, AL, MS
Region IV: Eastern Midwest - OH, MI, IN, IL, WV
Region V: Mid States - KY, TN, MO, AR, OK, KS
Region VI: South- TX, LA
Region VII: North Central - WI, MN, ND, SD, MI/UP, IA, NE
Region VIII: Rockies - MT, WY, CO
Region IX: Southwest - NM, AZ, UT, NV
Region X: Northwest - OR, WA, ID
Region XI: California
Region XII: Alaska
Region XIII: Hawaii
These states are grouped in that they have similar hardiness zones and somewhat similar geography. They can be called whatever name you want as well, I just picked a name that I thought would describe where they are.
I realize it is not perfect. Idaho could be split east of the divide and west of the divide, I think there are five or six hardiness zones in Idaho. California could be split. Alaska has some areas that would be a lot closer to what Washington has as well.
Use it, tweek it, or throw it in the trash. Just thought I would put something together to start from.