Corporations in the USA register at the State Level, usually with the Secretary of State’s office. Before spending any money you can check most state existing company names at the office links provided below. Some states also provide state trademark filing (separately from the Federal USPTO) but most of these have fallen into non-use or irrelevance.
Many of these offices also provide special information on their websites as to how to register different types of businesses. Some even have special help for small and minority owned businesses.
NOTE: These are purely informational guidelines. For details in your particular case, please consult your lawyer, accountant or state/county office.
A full list of state offices may be found at Secretary of State Offices .