"All right," John Dos Passos wrote in a rage over the execution of Sacco and Vanzetti, "we are two nations."

Oh, are we ever. And 77 years after Dos Passos penned those words, his two nations and ours bear an almost spooky resemblance.

The most striking, the most overwhelming fact about the 2004 vote is how closely it resembles the 2000 vote. Think of it: Since November 2000, the twin towers have been obliterated, we've gone to war preemptively and under erroneous pretenses in Iraq, George W. Bush has become the first president since Herbert Hoover to have jobs shrink on his watch, our standing in the world has diminished nearly everywhere. And how did all this affect the electoral map? A shift of 17,000 votes turned New Hampshire (four electoral votes) from red to blue, while a shift of 12,000 votes turned New Mexico (five electoral votes) from blue to red.

The battle lines of the cultural civil war that emerged in the 2000 contest have shown themselves to be all but impermeable to even the most earthshaking events. What did change between 2000 and 2004 was the capacity of the two parties to mobilize the forces behind their own lines. The Democrats did a splendid job of turning out their vote. The Republicans did a stupendous job of turning out theirs.

The exit polling -- amended, adjusted, corrected for reality -- shows the magnitude of the shift. In 2000 Democrats constituted 39 percent of the electorate and Republicans 35 percent. This year Democrats and Republicans each constituted 37 percent of the electorate. Four years ago, moderates made up 50 percent of the voting public and conservatives 29 percent. On Tuesday the moderate share of the electorate declined to 45 percent, while conservatives boosted their share to 34 percent.

The Republicans didn't get these figures by winning millions more political conversions than the Democrats: The numbers of 2000 Gore voters crossing over to vote for Bush this time and 2000 Bush voters crossing over to vote for Kerry seem about equal. Rather, they boosted their totals in small towns and hamlets, among Protestant evangelicals who don't often vote, beyond nearly everyone's expectation but their own. Karl Rove's strategy -- that Bush could attain a majority by a super-mobilization of the Christian right -- was vindicated and then some on Tuesday.

What Bush won on election night was a narrow "moral majority." The overwhelming support the president won among traditionalist churchgoers of modest means was rooted in an affinity of values. There's no evidence to suggest that Bush's "Medicare reform" -- his term for a huge giveaway to the prescription drug industry -- yielded him any votes at all.

Although Bush claims a mandate for his right-wing economics, that's clearly not what won him and other Bush Republicans the support of his evangelical base.

Time was when the right bemoaned liberals' reliance on identity politics, but no one has played the identity card more expertly than Bush and Rove. Stoking fears of cultural deviance and cosmopolitan ascendancy, the Republicans ran against John Kerry as, above all, an alien. In the reddest precincts of red America, Republicans question whether Kerry and the Democrats are Americans at all.

We've been here before -- when we had the two nations that Dos Passos wrote about. Our last two elections look increasingly like those of the mid-1920s, when our nation was also divided along cultural lines, the old-line rural and hinterland Protestant stock arrayed against the new immigrant-Catholic America that had taken over the Northeastern and Midwestern big cities and that, in the person of Democrat Al Smith, was seeking the presidency. Democrats didn't know how to cross the political dividing lines of the '20s any more than they do today. It took the Great Depression to make those lines crossable, and then Franklin Roosevelt re-divided the nation along lines of class that kept the Democrats in power for many years.

Democrats can't wait for another depression to restore them to power; the risk that long-term Republican rule poses to civilization is a touch too high. They need candidates and a language that even the worst good-old-boys recognize as American. That doesn't mean selling out Social Security, much less abandoning economic progressivism: 72 percent of the voters in the Bush state of Florida and 68 percent in the Bush state of Nevada voted on Tuesday for initiatives that raised the minimum wage. But it does mean that so long as the boundaries between blue and red America seem so fixed, the Democrats must be able to come off as Americans behind the other guys' lines.