The Smallest Winning Map Ever

A few days ago, Matt Yglesias put up a blog post in which he came up with the smallest possible winning electoral college map under the current vote distribution. He calculated this by sorting the 51 voting areas (i.e., states plus D.C.) in descending order by population density, and tacking states onto the map in that order until he had 270 electoral votes. D.C. was first, obviously, followed by New Jersey and then various other states. In the end he got a map with 627,421 square miles making up exactly 270 electoral votes and beating out the 268 electoral votes of the other 3,166,662 square miles of the country, just 16.5% of the country's land mass constituting a winning coalition. Actually, Alaska all by itself is bigger than these states which constitute an electoral majority. It's a majority of the people, though, with 166,439,539 living in the Yglesias victor states against just 142,306,179 in the losing states. That's a population density of 265.3 people per square mile in the winning states, and 44.9 people per square mile in the losing states.

Okay, cool. But the American population is a good deal less clustered in the Northeast than it used to be, so I got to wondering whether the smallest winning map might have been even smaller in the past. Using the 1960 census apportionment figures, i.e. the first batch after the addition of Alaska and Hawaii, I was able to craft an even smaller winning map:

Those blue states take up just 559,605 square miles, with 3,234,478 square miles of red territory, and an exact 270-268 electoral margin. My calculation method was a bit different from Yglesias'; instead of calculating 1960 census population density, I simply calculated electoral vote population density, and added until I hit 270. California was the tipping-point state, and since it got me to 284 EV's, South Carolina and West Virginia, only slightly more vote-dense than California, were superfluous. Incidentally, using this same method for the 2010 figures got me to the same map as Yglesias, though through a slightly different method. Whereas he added on the densest states until he hit Michigan, and then had 282 EV's, took Michigan back out to get down to 266, and added on New Hampshire to hit 270, I added on the most vote-dense states until I hit North Carolina, which got me to 282 EVs, and then subtracted off South Carolina (9) and Vermont (3). Somewhat confusingly, it doesn't look to me like Michigan is even in consideration; unless I'm really missing something, it is not, as he says, the 18th most densely populated state.

That's as far back as you can go, obviously, with Alaska and Hawaii still included, and since one of those two states in particular changes the geographic footprint of this country quite substantially the direct comparisons sort of end there. But just for fun, let's also look at the figures using the 1920 census apportionment, the first after all 48 continental states were added to the rolls. Here, we can get 268 electoral votes (enough to win, since there were only 531) with just 481,569 square miles, with 2,638,247 square miles taking the other 263 votes (the total is smaller, because we're missing Alaska):

Frustratingly, if you swapped out South Carolina and Virginia for Missouri, which would remove a bit more than 5000 square miles, you'd end up with 265 electoral votes in the blue states, and 266 in the red states. So I think this is probably the smallest possible winning electoral map since the continental United States got itself filled out. For whatever that's worth.