Not too long ago, political analysts assumed the Republicans had a clear advantage in the Electoral College, the system according to which each state, based on population, is given electors that in almost all cases are awarded on a winner-take-all basis. Today, it's the Democrats who have the edge.
Start by looking at the past seven presidential elections, three won by Republicans, four by Democrats. Then put most states that went for one party in five of these seven elections into the red column for Republican, blue for Democrat and purple or toss-up for the others.
Three are caveats: North Carolina and Virginia voted Republican until recently; the trends, however, are so pronounced that they are more purple than red. Conversely, West Virginia voted Democratic in three of these contests, but has moved safely into the red ranks.
BLUE: The District of Columbia and 20 states, mainly on the coasts and in the progressive upper Midwest, with 256 electoral votes, are the Democrats' base.
RED: 23 states, with 188 electoral votes, including much of the South, the Plains and Rocky Mountains states, are reliably Republican.
There are seven purple states -- Florida, Ohio, North Carolina, Virginia, Colorado, Nevada and New Hampshire -- with 94 electoral votes.
The upshot: In any normal election cycle, the Republicans have to win Florida and Ohio and at least three of the other five. Or they have to turn around some blue states, such as Pennsylvania and Iowa.
Politics do shift. In 1988, the Republicans won California, Michigan, Pennsylvania, New Mexico, Connecticut, Maryland and Vermont; all now are considered safely part of the blue base.
(Albert R. Hunt is Washington editor at Bloomberg News and a Bloomberg View columnist. Follow him on Twitter.)
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