On Sept. 19, 1977, a day that became known as "Black Monday" throughout the steel industry, Youngstown Sheet and Tube of Ohio announced the closing of its Campbell Works, which had employed more than 4,000 people. It was the start of a wave of plant closings that swept from Cleveland to Buffalo, across the Monongahela Valley into West Virginia and Kentucky.

Now, more than a decade later, the undertow from that wave is about to wreak political havoc on those same communities. The industrial upheaval that decimated the automobile, fabricated metal and steel industries has become a driving force in the transfer of political power from the North and East to the South and West, from Michigan, Ohio, Pennsylvania and New York to Florida, Arizona, California and Texas.

Economic hardship led first to stagnant population growth. Now, in combination with the 1990 census and both legislative and congressional redistricting, it will be translated into loss of political power in the 1990s. And the areas that suffered the most severe economic troubles -- areas where Democratic voting margins grew during the decade -- will experience the most severe loss of power both in Congress and in state legislatures.

For example, in Ohio's 17th Congressional District, which encompasses Youngstown and what was core steel manufacturing terrain in the Mahoning Valley, current estimates are that the district is nearly 90,000 people short of the 576,000 required for a post-1990 congressional district in that state. The worst shortfall -- 154,000 people -- is in Detroit's slums, Michigan's 13th Congressional District, represented by retiring Rep. George W. Crockett Jr. (D). Population shortfalls in the Detroit metropolitan area effectively guarantee a Democratic bloodbath as local legislators and members of Congress struggle to survive a sure loss of seats.

Between 15 and 19 congressional seats will shift among states, but that will account for only part of the transfer of power. Within states, the regional balance of power also will shift, almost always from older cities to the more prosperous suburbs.

These shifts within states are likely to have very specific political repercussions. The members of Congress representing districts that are losing the most population have much stronger ties to organized labor than the congressional average. As a result, organized labor, which has been steadily losing ground, is likely to see its number of hard-core supporters dwindle further in the 1990s.

In the other half of the redistricting equation, the nation's booming areas -- primarily high-growth beltway suburbs such as Troy, Mich., just beyond Detroit, or Cobb and Gwinnett counties on the outskirts of Atlanta -- are about to be rewarded with growing numbers of representatives in Congress and state capitols. With one main exception -- regions of high Hispanic growth in the Southwest -- the areas that will benefit from redistricting have tended to be Republican, especially in presidential elections.

This can be seen in a comparison of the voting results in the 50 congressional districts that gained the most population during the last decade, enough to create 14 new congressional districts, and the 50 with the sharpest declines, cumulative losses equal to at least nine House seats.

In the 50 districts that grew the most, Republican George Bush averaged more than 60 percent of the vote in the 1988 presidential election. In those 50 districts that lost the most population, Democrat Michael S. Dukakis won with an average of about 55 percent of the vote. Similarly, the Institute for Southern Studies found that southern counties that cast decisive 2 to 1 or better majorities for Bush grew during the 1980s at twice the rate of those counties that cast majorities for Dukakis.

These demographic trends should clearly benefit the Republicans, but demography traditionally has been subordinate to political power when it comes to redistricting. Very similar pro-Republican population trends occurred from 1970 to 1980. But in 1982, after the nation's districts were altered to account for the shifts, the Democrats picked up 26 House seats. The gains were due in part to the recession of 1981-82 but also were aided by Democratic control of the redistricting process in California and Florida, two of the three redistricting jewels (the third is Texas).

The gubernatorial and state legislative elections this year will, in most cases, determine which party will control the redistricting process in key states for the 1990s. In the early skirmishes, the Democrats have come out ahead.

In 1989, Democrats retained full control of the three redistricting "legs" -- the governorship, state House and state Senate -- in Virginia and took full control in New Jersey. Virginia is expected to gain a seat, and New Jersey may lose a seat. In addition, in June Democrats defeated two Republican-backed California initiatives designed to take power over the redistricting process away from the state's Democratic-controlled legislature.

If new congressional and legislative district lines are determined by political power, rather than by the courts, the Democrats enter the 1990 elections with one major advantage: In the states that stand to gain or lose at least two House seats, the most favorable Democratic scenario gives the party complete control of a net of six: California (+7), Florida (+3 or 4), Illinois (-2), New York (-3), Pennsylvania (-2 or 3) and Texas (+3 or 4).

Conversely, the most favorable Republican scenario gives the GOP full control in only one major redistricting state, Arizona, which is not certain of gaining two new House seats, and divided control in all the other key states.

Divided government usually results in compromise or extended court battles over disputed plans. It is for this reason that Democrats and Republicans are gearing up for what is expected to be a grueling series of court cases. During the 1980s, changes in the Voting Rights Act and Supreme Court decisions have significantly increased the political leverage of minorities in redistricting.

The importance of the courts was reflected in a mid-1980s struggle for control of the California Supreme Court. In addition to the widely publicized controversy over California Chief Justice Rose Bird's opposition to the death penalty, one of the GOP's major reasons for defeating her and two liberal colleagues in 1986 election was to gain a pro-Republican majority on the California Supreme Court in anticipation of redistricting disputes.

But before the courts get involved, redistricting is a supremely political process dominated by elected officials: governors and state legislators. Interviews with Republicans and Democrats produced a consensus on the political lay of the land at this stage of the election process that will determine who those public officials are:The Sunbelt

The key elections this year are the gubernatorial contests in California, Florida and Texas. In Florida, former senator Lawton Chiles now leads Rep. Bill Nelson in Democratic primary polls, and Chiles is widely viewed as a formidable challenger to Gov. Bob Martinez (R), who continues to have high unfavorable ratings.

Florida Republicans also are seeking to take control of the state Senate, where they are the minority in a 23 to 17 split. If they succeed, it would mark only the second time in the past 100 years that a southern state legislative body was taken over by the GOP. The first was Tennessee, where the state House turned Republican for one term in 1968. But in Florida, a Republican takeover of the state Senate in all likelihood would last a decade.

The legislatures in Texas and California are expected to remain firmly Democratic, making the gubernatorial contests in those states even more significant. In Texas, Democratic nominee Ann Richards remains 8 to 12 percentage points behind GOP rival Clayton Williams. Richards also has been suffering from negative public opinion poll ratings that are as high as her positive ratings and from a sluggish fund-raising operation.

In California, the contest between former San Francisco mayor Dianne Feinstein (D) and Sen. Pete Wilson (R) is very close, with each emerging as a marginal leader in different polls.

Arizona, which now appears likely to gain only one congressional seat, had been firmly Republican through most of the 1980s. More recently, however, severe ideological splits in the GOP, many centering on impeached former governor Evan Mecham (R), who is seeking to return to office, have given Terry Goddard, Democratic former mayor of Phoenix, a good shot at the governorship. Arizona Democrats also assert that public discontent with the GOP gives them an outside chance of taking control of the legislature, but Republicans discount that possibility.

In Georgia, which may gain two House seats, the Democrats are virtually guaranteed continued control of the legislature. Republicans expect state House Minority Leader Johnny Isakson to be the GOP gubernatorial nominee. His chances of winning in the heavily Democratic state would probably increase if the Democrats nominate former Atlanta mayor Andrew Young, who is black. The Midwest

In Ohio and Michigan, the GOP appears likely to retain control of the state senates, guaranteeing that the state governments will be divided because the Democrats appear assured of retaining control of each state's House. In Ohio, GOP gubernatorial nominee George V. Voinovich, former mayor of Cleveland, has a decided edge at the moment over Democrat Anthony J. Celebrezee Jr., the attorney general. In Michigan, Gov. James J. Blanchard (D) is considered likely to win a third term, but state Senate Majority Leader John Engler (R) is giving him more of a challenge than many expected.

Republican strategists have little hope of taking over either branch of the legislature in Illinois, and all the redistricting cash and staff commitment is going into the race for governor between Jim Edgar (R), the secretary of state, and Neil Hartigan (D), the attorney general. The East

Democratic governors Mario M. Cuomo in New York and Bob Casey in Pennsylvania look very strong in the two major East Coast redistricting states, and the major GOP concern in each is that the weakness of the Republican gubernatorial candidate could undermine efforts to retain GOP control of at least one branch of the legislature.

In New York, the GOP controls the Senate by a 34 to 27 majority, and Cuomo has put his prestige on the line in a drive to take over the Republican bastion. Democrats are banking on the tactic of running a number of candidates who support abortion rights, many of them women, against Republican incumbents. In Pennsylvania, the GOP controls the Senate 27 to 23, and the Democrats the House 104 to 99; both are major battlegrounds.

The ultimate target of contests from seemingly minor state legislative seats to the governorship of California is control of the House of Representatives, the mainstay of Democratic power in the federal government for the past 36 years.

Democrats acknowledge that their control over the redistricting process in 1980 gave them about 25 seats more than they would have received under a technically neutral process. Continued GOP failure to significantly dent Democratic control, which now stands at 257 to 176 with two vacancies, has been the source of major frustration for the Republican Party, while Democrats have used their House-based power to act as a brake on Republican administrations and, from 1981 to 1987, on the GOP-controlled Senate.