About 7 million Americans have registered to vote since 1994 because of the "motor voter" law, according to the Federal Election Commission.

As a result, registration among the voting-age population rose to 70.15 percent in 1998 -- the highest percentage in a non-presidential election year since 1970, the commission said yesterday.

The National Voter Registration Act, which took effect in 1995, was designed to make registration easier.

The law required 44 states and the District to let people register by mail, when they renew their driver's licenses and when they apply for welfare or disability benefits.

But an increase in registration doesn't necessarily mean higher turnout in elections. Actual turnout declined between 1994 and 1998, said Curtis Gans, director of the Committee for the Study of the American Electorate. The percentage of people casting votes declined from 39 percent of those eligible to 36 percent, he said.

The FEC said motor vehicle offices yielded the highest volume of registration applications -- 43 percent -- while 25 percent of new registrations were by mail.

The number of all registered voters rose from 124.6 million in 1994 to 136.6 million in 1998, a 10 percent jump.

Some of the increase would have occurred anyway, as the number of people reaching voting age increased, said Bill Kimberling, deputy director of the FEC's Office of Electoral Administration.

Idaho, Minnesota, Wisconsin, North Dakota, New Hampshire and Wyoming were exempted from the law because they register voters on Election Day or not at all.

The FEC study also excluded Nevada, which did not reply to the commission's questionnaire.