Maps: Primary votes as % of general election votes

While we wait for tonight's returns from the final two Democratic primaries, in Montana and South Dakota, here are a few maps that suggest the strengths and weaknesses of Barack Obama in states thAt have already held primaries. (Caucus states, among them Alaska and Hawaii, are not included because they attract far fewer voters and are not really comparable to general elections.)

The first map compares his primary vote to all votes cast in the 2004 general election. The darkest blue areas are where he has already attracted, in the primaries, more than 50 percent of the votes cast in November 2004. These areas represent his bedrock support: majority-black counties across the South and pockets of highly educated professionals mostly in the North. The map suggests, to no one's surprise, that Obama already has the District of Columbia and Vermont in the bag. Mississippi is not so easily won, as Obama's strength is mostly in lightly populated counties.

The second map shows how much progress Obama has already made toward getting the same number of votes that John Kerry won in the 2004 election. In most of the country, he seems most of the way there, but the Appalachian region is a glaring exception. The swing states of Ohio and Virginia are of particular concern: Even if Obama outpaces Kerry in the northern parts of those states, he could be undone by his inability to win over Appalachian residents who were perfectly willing to vote for "liberal elitist" Kerry.

But if supporters of Obama and Hillary Clinton unite, the Democrats could have a sizable advantage in November. As our last map shows, the total votes cast in Democratic primaries this year would be more than enough to win in most counties -- if the turnout were the same as in 2004. The state of Indiana is particularly startling on this map. It hasn't voted for a Democrat since 1964, but the combined vote for Obama and Clinton (nearly 1.3 million) would have been enough for an clear victory in 2004 (when about 2.5 million people voted). Of course, the Indiana primary turnout may have skewed by the fact that the Republican race had long been settled by that late date -- and maybe by Rush Limbaugh's exhortation for Republicans to cause mischief by voting in the other party's contest. (FYI: New York's light color on this map is at least partially attributable to the the fact that its Democratic primary was limited to registered Democrats; most other states had "open" primaries that also attracted independents.