The States maintains a database of all businesses registered in the State. You can utilize them to check on businesses you are considering doing business with.
Alabama
Hawaii
Massachusetts
New Mexico
South Dakota
Alaska
Idaho
Michigan
New York
Tennessee
Arizona
Illinois
Minnesota
North Carolina
Texas
Arkansas
Indiana
Mississippi
North Dakota
Utah
California
Iowa
Missouri
Ohio
Vermont
Colorado
Kansas
Montana
Oklahoma
Virginia
Connecticut
Kentucky
Nebraska (must subscribe)
Oregon
Washington
Delaware
Louisiana
Nevada
Pennsylvania
West Virginia
Florida
Maine
New Hampshire
Rhode Island
Wisconsin
Georgia
Maryland
New Jersey
South Carolina
Wyoming
