From the trade journal, Wines & Vines . . .
As of 12/31/2012, there are now almost 7,500 wineries in the US, and over 8,000 wineries in North America -- broken down as follows:
Bonded wineries in the US = 6,439 (in all 50 states)
"Virtual" wineries in the US = 1,059
That's 7,498 wineries in the US. Add in the combined figure for Canada and Mexico of 548, and the total is 8,046 wineries in North America.
Six US states and one Canadian province have 200+ wineries each within their borders:
California = 3,532
Washington = 670
Oregon = 544
New York = 310
British Columbia = 239
Virginia = 222
(Another 6 states and one province have between 100-199 wineries.)