here's a list from pennsylvania...
1. Fowler's Toad-(Anaxyrus fowleri) formerly (Bufo fowleri)(P)
2. AmericanToad-(Anaxyrus americanus) formerly (Bufo americanus)(P)
3. Eastern Spadefoot Toad (Scaphiopus holbrooki)(P)
4. Bullfrog ((Lithobates catesbeianus) formerly (Rana catesbeiana)(P)2010
5. Eastern Gray Treefrog (Hyla versicolor)(P)
6. Wood frog (Lithobates sylvaticus) formerly(Rana sylvatica)(P)
7. Southern Leopard Frog (Lithobates sphenocephalus utricularius.)formerly Coastal Plain Leopard Frog (Rana sphenocephalalus utricularius),(P) 2010
8. Spring Peeper(Pseudacris crucifer) formerly Northern Spring Peeper (Pseudacris crucifer crucifer)(P)
9. Green Frog (Lithobates clamitans melanotus) formerly Northern Green Frog(Rana clamitans melanota)(P)
10. New Jersey Chorus Frog (Pseudacris kalmi) formerly(Pseudacris ferairum kalmi) 2010
11. Mountain Chorus Frog (Pseudacris brachyphona)
12. Pickerel Frog (Lithobates palustris) formerly (Rana palustris)(P)
13. Upland Chorus Frog (Pseudacris feriarum) formerly (Pseudacris feriarum feriarum)
14. Northern Leopard Frog-(Lithobates pipiens) formerly(Rana pipiens)
15. Northern Cricket Frog- (Acris crepitans) formerly Eastern Cricket Frog (Acris crepitans crepitans)(P)
16. Cope's Gray Treefrog (Hyla chrysoscelis)
17. Midland Chorus Frog (Pseudacris triseriata)formerly Western Chorus Frog
found here...
Pennsylvania Wildlife - Showing Reptiles and Amphibians of PA List Page
if you look here it seems that all the frogs in our area that might have black legs are endangered or protected species...
Pennsylvania Wildlife - Photo Gallery