That silence you heard on Tuesday was the sound of millions of new voters not going to the polls. Despite unprecedented registration drives all across the United States, 1984 voter turnout increased but slightly when compared with the last presidential election. About 53 percent of the country's voting-age population cast ballots this year, estimates Curtis Gans, director of the Committee for the Study of the American Electorate. That's about 1 percent better than 1980's showing.
''It is an increase, but it's minimal,'' says Mr. Gans. ''Given the (partisan) polarization in the country, and the registration campaigns, it's not what one would have expected.''
The small increase did reverse a 20-year decline in the percentage of US citizens that vote for president. Before the election, however, Gans and other experts had predicted that turnout could be as high as 55 percent of the voting-age population. These hopes were based on the fact that the voter-registration contest between the Democratic and the Republican Parties was unprecedented in scope and impact.
Rock star Cyndi Lauper made a video commercial urging young fans to register and vote; preachers and social workers across America labored to sign up their charges. In Texas, registration was up 20 percent over 1980; in California, voter rolls increased 13 percent.
''Everyone was predicting a 95 million turnout,'' says Colonel V. Doner, head of the American Christian Voice Foundation, a fundamentalist group involved in voter drives.
In the end, about 92 million votes were cast. The size of the Reagan landslide, says Gans, was a major reason that many of the missing 3 million voters stayed home.
''Most registration efforts were aimed at low-motivation voters - minorities, the poor,'' he says. ''In a landslide these people had even less incentive to go to the polls.''
Early network projections of Reagan's victory may have exacerbated the situation, although evidence of this is circumstantial. Of the 25 states whose polls closed after 9 p.m. Eastern standard time, 19 had declines in turnout. Of the 24 states that ended voting before 8:30, 14 (along with the District of Columbia) had increased turnout.
It was the Democrats who began the voter-registration race, on the theory that since more people claim to be Democrats than Republicans, a larger electorate could only help their cause.
This strategy apparently backfired, at least in the presidential race. First-time voters favored Ronald Reagan over Walter Mondale by 60 to 39 percent, according to a New York Times/CBS News exit poll.
And in the state with the largest increase in turnout - North Carolina with 3 .4 percent - the GOP was particularly successful, Republicans point out.
Incumbent Sen. Jesse Helms ran to victory over his strong Democratic challenger, Gov. James Hunt. Three incumbent Democratic representatives in North Carolina were defeated.
''We won the registration fight, the get-out-the-vote fight,'' claims Sen. Paul Laxalt (R) of Nevada.
Evidence suggests that the composition of the US electorate did not change much this year, experts say.
Four years ago, 53 percent of the voters were women, according to Census Bureau statistics based on asking people their behavior. About 9 percent were black. Some 12 percent of the women were age 18 to 24 years.
''No (demographic group) has really been increasing their voter percentage over the past 15 years,'' says Martin O'Connell, a census official. ''I don't expect to see much change when we crunch the numbers for '84.''
In fact, the only group that has shown a marked increase in electoral participation recently, says O'Connell, is voters 6 feet 5 inches or more tall.
Other analysts argue that blacks are also increasing their percentage of voter turnout.
Still, according to the Census Department, despite the voting drives, the US electorate remains disproportionately white, older, and well off.
In 1980, 61 percent of eligible whites voted, while only 51 percent of eligible blacks went to the polls. (In 1976 the black turnout was 49 percent.) The voting turnout of Hispanic US citizens was 44 percent.
Four years ago, only 4 of every 10 citizens age 18 to 24 bothered to vote, according to Census Department data. As people grow older, however, they are much more likely to troop to the polls: 65 percent of those 65 and over voted.
And the well-off are still much more likely to stand up and be counted than those less financially fortunate. Fifty-nine percent of white-collar managers voted in 1980, while turnout among the unemployed was 34 percent.