It doesn't. On the Democratic side, in fact, the two remaining candidates have been averaging about the same number of votes per delegate won, because the Democratic contests are proportional. Each delegate Sanders won in Washington will end up having required about 262 votes — the second-cheapest (if you will) delegates in the Democratic contests so far — but the delegates won by Hillary Clinton will cost the same.
On the Republican side, where the contests use a hodge-podge of different allocation methods and winner bonuses, the distribution looks different. Donald Trump's delegates have been far less expensive in terms of votes than those of Ted Cruz or John Kasich.
Trump's delegates have cost him about 10,700 votes apiece, according to our calculations from The Post's delegate tracker and U.S. Election Atlas's vote counts. If the Democrats and Republicans had the same number of delegates, that's a bit lower than the cost to the two Democrats. Ted Cruz's delegates, though, have taken about 12,400 votes apiece -- and Kasich's nearly 20,000.
To understand why, look at the states. In Florida, Cruz and Kasich got more than 560,000 votes combined -- but no delegates. In Alabama, Marco Rubio got one delegate for his 160,000 votes. Those disproportionate allocations mean wide swings in the value of a delegate from state to state.
For the Democrats, the cheapest state was Maine (followed by Washington) and the priciest, Illinois.
For the Republicans, it varies from candidate to candidate.
The biggest gap in the value of delegates on the Democratic side was in Mississippi, where Clinton's delegates cost her about 5,700 votes each and Sanders's cost him about 9,100. That's excluding Vermont, where Sanders's sweep of the delegates meant that Clinton got zero -- despite 18,000 votes. That breaks the system.
Which is why it's hard to figure out the biggest gap on the Republican side: Lots of states where people end up with no delegates whatsoever.
So Donald Trump leads the Republican race by spending the fewest votes for each delegate -- and Hillary Clinton leads the Democrats by spending the most.
A neat little encapsulation of the two races overall.