Would doubling the size of the House have affected the Electoral College outcome in 2016?
A common mantra after the presidential election sounded something like this: "California is so much larger than Wyoming, but a vote cast in California has only a third of the value of a vote cast in Wyoming in the presidential election." Or something like that. This, in turn, is often a proxy for criticizing the Electoral College.
The Electoral College allocates electors based on the total number of members of the House and Senate each State has--and, as each State is guaranteed at least one House representative, no matter how small, and exactly two Senators, no matter the size, each state will receive at least three electoral votes. With a House of 435 members, a Senate of 100 members, and 3 votes for the District of Columbia, we get 538 electoral votes, 270 needed to win.
In the 2016 presidential election, that looked something like this: Californians cast over 14 million votes for president. Given California's 55 electoral votes, that works out to about 257,847 votes cast per electoral vote. In Wyoming, there were 255,849 total votes cast for president. That works out to about 85,283 votes cast per electoral vote. And that's just about a 3:1 ratio. (Granted, the House is apportioned based on total population, not ballots cast, but let's stick with this metric for now. And, of course, this is a rather crude approximation of how to "weigh" votes, considering that these are winner-take-all states rather than votes-per-elector, but it has an understandable simplicity and rhetorical appeal.)
(Here, too, it may be worth noting that this fairly grossly overstates a single voter's power. Put in reverse, a California voter is providing 0.0000039 of the total value of a single electoral vote; a Wyoming voter is providing 0.0000117.)
In some ways, the real problem people have with this disparity is the United States Senate itself. But much of the reason that this disparity exists is because the size of the House of Representatives has not increased since 1911. The Reapportionment Act of 1929 capped the size of the House at 435 members, fixing it as it was in 1911--and, as a result, capped the size of the Electoral College. It meant that disparities in the Electoral College would increase as populations shifted.
Roughly doubling the size of the House to 871 members would give better representation based on total population. And it would do so without any need for a constitutional amendment--a simple statute from Congress could help equalize this spread. But would it have changed anything in the 2016 presidential outcome? Not really-it would smooth out some of the disparities but have no meaningful effect on the outcome (except to actually widen the margin of Donald Trump's victory).
Using the Equal Proportions Method, we can fairly quickly calculate how these 871 seats would be allocated based on the 2010 census. The smallest state in this scenario receives two House members. We'd then add in 100 electors for the Senate, another 4 electors for the District of Columbia, and come to a nice round 975 electoral votes: 488 votes to win. And like the five fictional Electoral College outcomes I provided recently, we can recalculate the 2016 election after our newly-constructed House.
By giving California a whopping 104 members in the House--and 106 electoral votes--we'd see the 2016 totals drop to 133,788 votes cast per electoral vote. In Wyoming, which would get a second member in the House and 4 electoral votes, it would have 63,962 votes cast per electoral vote. The California:Wyoming ratio would drop from 3:1 to 2:1. That would certainly improve the disparity, but hardly cure it.
And despite improving the disparity, we see little change in the overall outcome. (I assumed a winner-take-all in each state, despite Maine's and Nebraska's systems.) It yielded 547 electoral votes for Mr. Trump to 428 for Hillary Clinton--a comfortable margin of victory, and by raw pledged electors much larger than his actual 2016 victory. So while it might help reduce some of the rhetoric regarding disparities in vote power across states--and improve some of the actual voting power--it wouldn't offer any dramatic change to our system.
I have the complete breakdown of electoral votes below. If you'd like to reverse-engineer the House figures, simply subtract two from each state.