The National Motor Vehicle Title Information System allows potential used car buyers to check the title, odometer reading, accident history and other information for a fee of less than $5.
The system was first proposed in the early 1990s, but was stalled until consumer protection agencies took legal action forcing the federal government to enact the program. It is currently administered by the Justice Department.
All states, insurance carriers and junk yards are required to submit data on vehicles to the system, and states were required to comply by Jan. 1.
But the District of Columbia and four states -- Oregon, Illinois, Mississippi and Kansas -- have yet to submit records, saying they don't have enough money for the computer upgrades and clerical work needed to take part.
Justice Department officials said they are working with the states. Even without their participation, roughly 80 percent of registered vehicles in the United States are included.