Permission to work in or visit the United States must be obtained through the United States Citizenship and Immigration Services (USCIS). Embassies or consulates abroad do not have the authority to grant work permits yet they are allowed to issue visas for immigrant and nonimmigrant travel. In all cases, permission to work must be obtained in the United States by an employer who wishes to hire the individual.

The United States issues a confusing range of visas which are broadly divided into immigrant (permanent resident) and non-immigrant (temporary resident) visas. An immigrant visa gives the right to live and work in the United States on a permanent basis and to qualify for US citizenship after five years of residence. A non-immigrant visa allows the individual to enter and remain in the United States on a temporary basis (e.g., from six months to five years) and to accept employment in certain cases. This visa is generally used for tourism, medical treatment, business, temporary work or study.

This is just a sample of what you'll find in every complete USA city guide.