I won't be able to remember all of these, but let's try:
New York: (10) Plattekill, Hunter, Belleayre, Windham, Gore, Whiteface. Sterling Forest, Mt. Peter, Catamount, Thunder Ridge.
Vermont: (15) Mt. Snow, Hogback, Haystack, Stratton, Magic, Bromley, Roundtop, Okemo, Killington, Pico, Sugarbush, Mad River Glen, Stowe, Jay Peak, Bolton Valley.
New Hampshire: (2) Wildcat; Does Mt. Washington/Tucks count?
Massachusetts: (6) Berkshire East, Mt. Tom, Bousquet, Otis Ridge; Mohawk Mountain, Ma., Butternut.
Colorado: (4) A-Basin, Breckenridge, Copper, Vail.
Utah: (5) Alta, Snowbird, Brighton, Solitude, Park City.
California: (3) Squaw Valley, Alpine Meadows, Sugar Bowl.
45 total. (I will probably remember a few others). Not that many. But, I am a creature of habit.