Commercial transportation and trucking is a major, vital industry in America. To create uniformity in licensing standards, vehicles crossing state lines need apportioned vehicle registrations under the International Registration Plan – which is available in all states. Intrastate commercial vehicle registration also exists. Additionally, specialized permits for oversize and specialty carrier vehicles are also common in many states. A number of federal licenses from also apply to commercial transportation.
Being one of California and the nation’s major cities means San Diego is home to many businesses. However, the city’s licensing systems are fairly decentralized requiring business owners to apply to numerous departments including the city treasurer, planning and development and the police. Additionally, licenses from San Diego County, the state and sometimes the federal government are required in certain industries. San Diego's major industries include defense, international trade, shipping, tourism, manufacturing, research and real estate. The city's close proximity to Mexico and large natural harbor make it a gateway to commerce with Asia and Latin America.