Professional licensure in the United States
In the United States, the state governments have jurisdiction for issuing most professional licenses to individuals and corporations. In areas that naturally cross states borders, the national government may be the issuer. Thus the Federal Aviation Administration licenses pilots. The Federal Communications Commission certifies persons operating and repairing amateur and many (depending of their power and frequencies) commercial radio transmitters. The Environmental Protection Agency requires that technicians recycling Freon be examined. In many of these areas the federal government approves organizations (and, for the FAA, private examiners) to test and certify applicants who meet its standards.
Fields that are regulated and licensed vary among individual states. Among regulated fields are health care professionals (medical doctors, nurses); psychologists; lawyers; teachers; engineers; social workers, occupational therapists, architects; tradesmen (plumbers, electricians), and certain service industry workers (bartenders; massage therapists; barbers).
It is now possible to verify an individual state license in all states online, via websites set up by each state government, by different agencies. Some private websites provide links to all such databases, in one location.
License standards and issues
Licensing standards can differ widely from state to state. Also, the fields and occupations which states require to be licensed may differ widely. Some states may require a written examination for a license, while others may require several years of field experience as a student or intern. Some states have license requirements which are fairly uncommon among other states; for example, four states require licensing for interior designers.  The State of Illinois requires four exams to become a "nail technician," or manicurist.  Yet, there are states which do not license radiologic technologists and they are delivering ionizing radiation to the general public. Furthermore, some states which boast licensure only require a person to attend a "program in radiologic technology" to be eligible for licensure. The gold standard is a JCERT accredited 24 month program, but some states allow 6 week programs.  The radiologic technologist should also be credentialed by the national organization, "American Registry of Radiologic Technologists", which ensures the radiologic technologist adheres to a standard of ethics, is educationally prepared and clinically competent.
There is often debate about the level and type of regulation needed. In Texas, there has been recent debate about state regulations which prohibit horse floaters from working on horses if they are not licensed veterinarians. 
Some standards and procedures are the product of state boards working together. For example, the United States Medical Licensing Examination (USMLE) is a medical exam which was created by the Federation of State Medical Boards.
Illegal immigrants are not allowed to receive state or local public benefits, which include professional and commercial licensure.
- List of state verification sites, at noah-health.org. (New York Online Access to Health.) Archived from the original on 2012-04-14.
- List of state verification sites, especially for medical licenses, at circare.org (Citizens for Responsible Care and Research)