Actually the Commission on Superhuman Activities has the final word. S.H.I.E.L.D. is trying to build up the C.S.A.'s capabilities to enforce the S.H.R.A. S.H.I.E.L.D. is an international agency, not an American one and they are also helping Canada, Israel, and the United Kingdom develop their registration acts.
As for the teams, not all of them have been developed yet:
Colorado
Thunderbolts (Thunderbolts Mountain, Denver)
Active: Green Goblin, Moonstone, Songbird, Venom/Scorpion, Bullseye, Penance, Radioactive Man, Swordsman
Inactive: Ajaxis, Aqueduct, Atlas, Bloodstrike, Bushmaster, Death Adder, King Cobra, Rattler, Scarecrow, Silk Fever, Smiling Tiger, Vector, Whiplash, Zaran
Conneticut
The Initiative (Camp Hammond, Samford)
Staff: Gauntlet, Justice, Yellowjacket, War Machine, She-Hulk, Black Widow, Ares, Beast, Hellcat, Ms. Marvel, Danielle Moonstar, Nighthawk, Tigra, Wonder Man, Baron von Blitzschlag
Trainees: Cloud 9, Trauma, Komodo, Hardball, Thor Girl, Ultra Girl, Batroc, Arana, Patriot, Stature, Hawkeye, Vision, Wiccan, Speed, Hulkling, Slapstick, Rage, Bengal, Debrii, Scorpion, Stingray, Constrictor, Network, Two-Gun Kid, Gargoyle, Alex Power, Triathalon, Rocket Racer, Puma
New York
Avengers (Stark Tower, Manhattan, New York City)
Iron Man, Ms. Marvel, Wasp, Black Widow, Wonder Man, Sentry, Ares
Falcon (Harlem, New York City)
Fantastic Four (Baxter Building, Manhattan, New York City)
Mr. Fantastic, Invisible Woman, Human Torch, the Thing, Black Panther, Storm
Heroes for Hire (Golden Dragon Restaurant, Chinatown, New York City)
Misty Knight, Colleen Wing, Black Cat, Tarantula, Shang-Chi, Humbug
Phone Ranger (New York City)
X-Factor Investigations (District X, New York City)
Multiple Man, Wolfsbane, Strong Guy, M, Syrin, Rictor, Layla Miller
X-Men (Xavier Institute for Higher Learning, North Salem, Westchester County)
Active: Cyclops, Emma Frost, Beast, Shadowcat, Colossus, Wolverine, Iceman, Nightcrawler, Darwin, Havok, Polaris, Marvel Girl, Warpath, Rogue, Cannonball, Mystique, Lady Mastermind, Karima Shapandar
Inactive: Angel, Karma, Magma
Students: Elixir, Surge, Hellion, Armor, Dust, Mercury, Rockslide, Wither, Celeste Cuckoo, Mindee Cuckoo, Phoebe Cuckoo, Anole, Indira, Loa, Match, Wolf Cub, Pixie, Trance, Bling!, Onyxx, Nezhno, Blindfold, X-23, Ernst, No-Girl
Texas
Rangers - Firebird, Phantom Rider, Red Wolf, Shooting Star, Texas Twister, Armadillo, Living Lightning
Washington
Skyhawk
Wisconsin
Great Lakes Initiative (Milwaukee) - Mr. Immortal, Big Bertha, Flatman, Doorman, Squirrel Girl
Other
Aegis
Arachne (Omega Flight - Canada)
Asylum
Bishop (O*N*E)
Black Crow
Blade (S.H.I.E.L.D.)
Blazing Skull
Boomerang
Brother Voodoo (S.H.I.E.L.D.)
the Captain (Nextwave)
Captain Marvel (Negative Zone Prison Alpha)
Deadpool (Agency X)
Doc Samson (S.H.I.E.L.D.)
Elisa Bloodstone (Nextwave)
the Fixer (C.S.A.)
Hindsight Lad
Mach-IV (C.S.A.)
Machine Man (Nextwave)
Magdaline
Masked Marvel
Monica Rambeau (Nextwave)
Moon Knight
Morbius (S.H.I.E.L.D.)
Paladin (S.H.I.E.L.D.)
Quasar
Silhouette
Silverclaw
Sleepwalker
Solo
Tabitha Smith (Nextwave)
Timeslip
Tiger Shark
Toxin
Unicorn
U.S. Agent (Omega Flight - Canada)
White Tiger
As you can see, most heroes right now are either in training or in New York which obviously has to come first. The Great Lakes Champions were already in Wisconsin. Since the President frequently goes to his ranch in Texas, I assume that the government formed the Rangers quickly to defend that state. Do you think that right away there will be instantly 50 superhero teams?