WASHINGTON - Seat belt use rates increased in North Dakota and 36 other states this year, a fact that federal highway safety officials attribute to increased awareness and police enforcement.

Arizona and Hawaii achieved seat belt use rates of more than 95 percent, the highest ever reported, the National Highway Traffic Safety Administration said. The national seat belt use rate in 2004 was 80 percent, also an all-time high.

Mississippi improved its seat belt use rate by 1.6 percent but still had the lowest rate in the nation at 63.2 percent. Massachusetts, Arkansas and South Carolina were the only other states with belt use rates at 65 percent or lower.

In North Dakota, officials found more than 67 percent of the population used seatbelts, an increase of 5.8 percent from 2003.

NHTSA Administrator Dr. Jeffrey Runge said seat belt advertising campaigns combined with police enforcement have helped boost the numbers. Most states collected their data in June, shortly after a $30 million national advertising campaign.

Primary seat belt laws, which allow police to stop a motorist for not wearing a seat belt, also may increase use levels, NHTSA said. Tennessee, which passed a primary belt law in July 2004, saw its belt use rise from 68.5 percent in 2003 to 72 percent in 2004.

Still, the contribution of primary belt laws appears to be mixed. Arizona, with the highest use rate of 95.3 percent, doesn't have a primary seat belt law; the other five states with use rates over 90 percent - California, Hawaii, Michigan, Oregon and Washington - have them. Puerto Rico, which had a use rate of 90.1 percent, also has a primary belt law.

Twenty-two states have primary seat belt laws. Most of the rest have secondary seat belt laws, which allow police to issue a seat belt ticket only to a driver stopped for another violation.

States collected data using roadside surveillance along highways and at intersections. NHTSA certified that each state used federal survey techniques. NHTSA didn't report data from New Hampshire because the state didn't use the proper techniques, a NHTSA spokeswoman said.

Peter Thomson, New Hampshire's director of highway safety, didn't return a call seeking comment Monday. Early this fall, Thomson said NHTSA was targeting New Hampshire because it is the only state without a seat belt law for adults. New Hampshire does have a primary belt law for youth younger than 18.

Numbers comparing use rates between 2003 and 2004 also weren't available for Maine and Wyoming because those states supplied no data in 2003, NHTSA said.

(On the Net: National Highway Traffic Safety Administration, http://www.nhtsa.dot.gov.)