This page provides direct linking to US state vanity plate registration websites. You may find details and procedures for registration on the appropriate state motor vehicle department website.

What Is a Vanity License Plate?

A vanity plate is a personalized license plate number in the United States. They are issued by every U.S. state and the District of Columbia. All states have a "Blue List" that contains a list of banned letter/number combinations, words, and phrases. So be prepared: your choice may be rejected if it is in the list.  

List of US states and websites:

Alaska Vanity License Plates
Alabama Vanity License Plates