Resident Fellow  Michael Barone

It's been a while since the Pennsylvania presidential primary has made any difference. You have to go back to 1984, when Walter Mondale beat Gary Hart there, or to 1980, when George H. W. Bush edged Ronald Reagan.

Pennsylvania was in the spotlight a week before the 1976 Republican national convention. Ronald Reagan chose its liberal senior senator, Richard Schweiker, to be his running mate, hoping to peel away enough Keystone State delegates to overtake Gerald Ford. It didn't work. Neither did Gov. William Scranton's brief campaign to stop Barry Goldwater in 1964.

The truth is that Pennsylvania, long the second most populous state and still number six, has been punching below its weight in presidential politics for a long time. Its only president, James Buchanan, presided over the breakup of the Union. He is widely regarded--outside precincts heavily afflicted by Bush Derangement Syndrome--as our worst president.

To understand the state today, it is useful to recall that 19th-century Pennsylvania developed a politics that was practical and protectionist--characterizations that hold true. The steel industry centered in Pittsburgh wanted high tariffs to keep out foreign steel and machines; protectionism and memories of the Civil War made Pennsylvania solidly Republican from 1865 to 1930. Sen. Joseph Grundy, president of the Pennsylvania Manufacturers Association, voted against the Smoot-Hawley tariff in 1930. It wasn't protectionist enough, he said.

As late as 1950, Pennsylvania's giant steel and coal industrials made it an economic behemoth. The state then had 7% of the nation's population, but has only 4% today. Its failure for many years to adapt to a changing economy has left it far behind.

Today, the central fact about Pennsylvania is that it is old: Some 15% of its residents are 65 or older, more than any other state except Florida. Not many people are moving out of the state any more, and some are moving in, especially to the counties near the borders of higher-tax New York, New Jersey and Maryland. The state's economy is finally diversifying; still, metro Pittsburgh is losing population because it has more deaths than births.

Politically, Pennsylvanians over the past 40 years have tended to be liberal on economic issues (favoring big government) and conservative on cultural issues. That leaves it closely divided between the two parties but at odds with the national trend, and the trend of the Democratic Party (at least in Bill Clinton's years as president) toward more conservative economics and liberal culture.

Within the state there have been conflicting party trends. In the 1980s, metro Pittsburgh and western Pennsylvania, hit hard by closings of steel plants, trended toward the Democrats and voted heavily against Ronald Reagan in 1984. The affluent Philadelphia suburbs, grateful for tax cuts, were heavily Republican and swung the state for Reagan that year, and for George H. W. Bush in 1988.

In this decade the two regions have moved in the opposite directions. Western Pennsylvania trended toward George W. Bush, while the Philadelphia suburbs voted heavily enough for Al Gore and John Kerry that Democrats carried the state narrowly in 2000 and 2004.

Democrats have had a harder time in U.S. Senate elections. Even as Republicans and Democrats traded the governorship every eight years since 1950, Republicans won each of the 14 regularly scheduled Senate races from 1964 to 2004. (Democrat Harris Wofford won a special election in 1991 to replace John Heinz after his death in a plane crash.)

The Democrats' problem? Cultural conservatives with strength in western Pennsylvania couldn't raise money or win votes from cultural liberals in the Philly suburbs, while Philadelphia-area liberals bombed in the west.

The Democrats solved this problem in 2006, when Gov. Ed Rendell and Senate Democratic campaign committee chairman Chuck Schumer pre-empted the field for Bob Casey Jr., a fervent opponent of abortion. They ordered feminist liberals to contribute to and vote for Mr. Casey to produce a Democratic Senate. It worked.

Pennsylvania's demography--elderly, downscale, Catholic--clearly favors Hillary Clinton in the Democratic primary. Her full-throated though occasionally overfrank support from Mr. Rendell helps her in his core constituency, the Philadelphia suburbs, which were favorably impressed by his record as Philadelphia mayor from 1991 to 1999 (the city, half black, will presumably vote for Barack Obama).

Western Pennsylvania, much like northeast Ohio but with fewer blacks, and the "T"--the area between the two metro areas plus the whole northern geographic half of the state--should be a piece of cake for her.

Polls tend to show Mrs. Clinton running stronger in Pennsylvania against John McCain than Mr. Obama. And the latter's comments that "bitter" voters in small towns will "cling" to "guns and religion" will probably not help him. It undercuts Mr. Obama's claim that he will be a stronger candidate in the general election.

Mrs. Clinton will claim that her primary victory (if it turns out to be that) in the nation's sixth largest state shows that she is the choice of the people--especially the white working class which has been the bedrock constituency of the Democratic Party since the 1930s. But the white working class is steadily declining as a Democratic constituency.

The demographic composition of the Pennsylvania electorate, which makes it more typical of the America of the 1950s than the America of today, means that its precedential value is limited to its 21 electoral votes (down from its peak of 38 in 1912-1928).

Pennsylvanians have kept quiet during most of our history. But they will make some noise when they vote tomorrow--and may make more difference than they have since the days of James Buchanan and Benjamin Franklin.

Michael Barone is a resident fellow at AEI.