All elections are, at their heart, a battle of the two parties' bases. The 2016 presidential election was no different.

There are lots of ways to slice and dice how and why Hillary Clinton lost on Nov. 8 what looked — by virtually every measure — like a race she could not lose. But, to me, the most compelling reason is this: She simply didn't excite or turn out the Democratic base enough.

This chart, which comes via the Republican polling firm Public Opinion Strategies, encapsulates Clinton's base problem nicely. It breaks down turnout from 22 key counties in six swing states — five of which Clinton lost (or, in the case of Michigan, looks likely to lose).

"In Virginia, the Clinton campaign was able to get the turnout they needed in Fairfax County — helping her win the state," reads the memo from POS. "But in the other states, note the significant turnout drops in
key Democratic counties in Wisconsin, North Carolina, Ohio, and Michigan."

That's spot on. In 13 of the 22 key counties identified above, turnout was lower in 2016 than 2012. While Clinton matched or, in many cases, slightly improved on President Obama's showing in these counties, her margins weren't enough to make up for the broader turnout drop.

Take Wisconsin, for example.  Here's how Clinton and Obama did in Milwaukee County, the largest county — by population — in the state.

Clinton: 288,986 votes

Obama: 328,090 votes

That's a 39,000 vote difference, Clinton lost the entire state by just more than 27,000 votes. So, yeah.

What the chart above suggests is the limits of organization. Clinton, like Obama before her, invested massive resources in building voter identification and turnout operations in every swing state. But, unlike Obama, Clinton wasn't able to supplement that organization with the requisite amount of organic energy and passion for her candidacy. The best organization in the world can't make up for a lack of enthusiasm.

That enthusiasm deficit within these 22 key counties almost certainly cost Clinton the White House. Politics is, after all, a game of inches.