WITH A RAZOR-THIN majority, Democrats in America’s Senate are struggling to pass a signature spending bill. Their woes stem in part from failing to win a bigger majority of votes, but also from the over-weighting of small states, which tend to be rural, in the upper chamber of Congress. Each state gets two senators. As Democrats have become the party of cities, the share of their voters that are packed inefficiently into a few big states has risen.

The constitution was designed to represent both places and people. And in 2020, Democrats’ nationwide margin of victory was big enough to overcome geographic handicaps. But in future, Americans’ growing taste for straight-ticket voting is likely to exacerbate the Senate’s imbalances.

In 2016 and 2020, the only time a state supported different parties’ candidates for the presidency and Senate was in Maine last year. And to win the Senate, Democrats need Republican presidential voters to split tickets. In a hypothetical scenario where everyone votes straight-ticket, each state’s relative partisan preference is fixed at the levels from last year’s presidential election and the two parties split total votes for Senate candidates evenly in every election, Democrats would win just 40 of 100 seats during a six-year Senate cycle.

Few legislative remedies exist for such a skew. The constitution bans amendments to Senate apportionment. And if straight-ticket voting were universal, it would take ten new blue states to close the gap.

In theory, however, voters could shrink this imbalance one by one, by moving to smaller states. The rise of remote work makes such choices more plausible. To test whether a hypothetical campaign of interstate migration could meaningfully reduce the disparity, we wrote an algorithm that determines how many Democratic voters would need to leave California to make the Senate fair to both parties over a full six-year cycle, and where they should go.

There were two clear groups of destination states. First, the best offence is often a good defence. Democrats hold both Senate seats in New Hampshire and Nevada, but their incumbents are vulnerable. Shoring them up would provide a counterweight to red-tinged former swing states like Iowa.

Next, one red state offers a seat swing per migrant twice as high as any other. In Alaska, which Donald Trump won by 36,000 votes, Democrats already get 40% of votes. Moreover, the state’s new ranked-choice voting system could reduce partisan fervour. Just 100,000 new Democratic voters would turn Alaska reliably blue.

True to its nickname, Alaska is probably the last frontier for political migration. Republicans typically win North and South Dakota, Wyoming and Montana by 100,000 votes each. Assuming average turnout, flipping all four solid blue would take 2-3m transplants—four times the number that move out of California per year—from left-leaning demographic groups.

The assumptions underlying these estimates may not come to pass. Parties’ coalitions evolve unpredictably, and split-ticket voting could make a comeback. But if Democrats do get desperate, moving to the frigid physical wilderness might help them to escape the political kind.■

Sources: David Shor; The Economist