Shift to the center

Congress's voting patterns in 1983 further underscore a long-term trend in the United States toward a national political culture. Such a trend strengthens the center at the expense of the ideological extremes.

After two years of a conservative White House, Congress as a whole voted distinctly more liberally in 1983, as if naturally shifting Washington's political weight more closely into an institutional balance.

Congressional voting in 1983 was revealing in another crucial sense. It was the first election after nationwide redistricting and a shift of seats to the South and West. It had long been claimed that the migration of Americans to the Sunbelt, followed by more congressional delegates in those regions, would lead to greater conservatism in national politics. A decade ago, such a pattern had failed to show up after post-1970 census redistricting. It has now failed to show up again after the post-1980 reapportionment.

Homogenization, rather than polarization or a weighting toward Sunbelt conservatism, is the apparent trend.

The importance of this should not be missed. According to a Monitor analysis of congressional vote patterns, based on statistics compiled by Americans for Democratic Action, the relative gap in regional voting averages has steadily closed the past two decades. The gap between the most liberal region, the East, and the most conservative, the South, shrank from an average 40-point gap from 1965 to 1975, to 22 points in 1983. Last year the South's congressional delegation averaged a 40 percent ADA rating, based on a scale of l00 percent for ''liberal'' votes on a wide range of issues. The East averaged 62 percent, the West 49 percent, and the Midwest 51 percent. The South showed the most dramatic shift from the year before, when it averaged 26 percent.

Last year, the conservative coalition of Southern Democrats (nicknamed ''boll weevils'') and Republicans that gave Reagan his Capitol Hill victories in 1981 and 1982 came together less often than in any year since 1964, Congressional Quarterly reports.

What's happening?

Partly 1983's voting - presaging 1984's - showed the effect of the last election. ''The new Democrats in the South were not boll weevils,'' says Congress expert Thomas Mann, ''they were national Democrats.'' ''The South has run through the generation of conservative recruits,'' adds Norman Ornstein, another Congress analyst. ''Except for their accents, the candidates recruited in 1982 were not unlike their Northern counterparts.''

The slipping into the past of segregated voting patterns and the legacy of racism is of course one factor in the South's joining the rest of the nation politically. But so are other forces - industrialization, clustering of new high-tech industries around university-metro centers in all parts of the nation, instant national communications, and the creation of a larger college-educated class which emphasizes common professional and cultural interests. Such forces lessen regional political differences.

In the 1960s, congressional delegations from states like North Carolina and South Carolina, reflecting their constituents' outlook, averaged in the deeply conservative single digits. North Carolina's congressmen in 1983 (after, by the way, a major Reagan-team defeat in 1982's races there) voted slightly more liberally than the national congressional average of 49 percent; in 1965 its average was 2 percent. Even the casual visitor to North Carolina's Raleigh-Chapel Hill area today would recognize its similarities to Boston's Route 128 high-tech community, or Ohio's Columbus region.

The delegation from Florida, which gained the most new congressional seats (five) in 1982's reapportionment, averaged a 38 percent ADA rating in 1983, compared with 19 percent in 1965 and 23 percent in 1970. Texas, another big gainer, also moved closer to the national political center.

None of this is to suggest that the United States has yet lost its regional distinctiveness in congressional voting. Virginia, for example, hangs in there as the most conservative state. Big states - New York, Ohio, Texas - still tend to typify their regions.

But looking ahead to November '84, it would be a mistake to anticipate signs of a distinctly conservative trend in US politics. The pressure on Congress and Reagan will again be toward the center.