There's some evidence, early on the morning of the women's protest march in Washington, that turnout at the event will be significant. Take, for example, this video.

On Friday, for the actual inauguration, the D.C. transit authority went out of its way to note that ridership was down compared with past inauguration days. Images on social media seem to suggest that the influx the agency will struggle to handle came 24 hours later.

We know that crowds for the inauguration of President Trump were more modest than years past. But why would the turnout at a protest of the president be higher?

One large reason is a simple one: More people view Trump negatively than positively.

On Friday, we looked at recent polling assessing Trump's popularity. In five recent polls (and a sixth, from Fox News, that came out later), Trump's favorability numbers were underwater, meaning more people view him unfavorably than favorably. In several polls, more than half the country says it views him unfavorably.

Running down the line, Trump's net favorability in those five polls is minus-12, minus-10, minus-9, minus-14 and minus-10. In the Fox poll, he's at minus-13.

That's an unusual position for an incoming president. Past presidents-elect earned net-positive reviews before taking the oath.

(Also unusual for an incoming president, of course, is that they normally earn more of the popular vote.)

Consider The Washington Post-ABC poll released this week. Forty percent of Americans view Trump positively — but 54 percent view him negatively. Meaning that 35 percent more Americans have a negative view of Trump than a positive one — so, all things being equal, turnout for a protest might be expected to be 35 percent higher.

But all things aren't equal. Other factors come into play.

For example, as the Weekly Standard's Jim Swift noted on Twitter, the inauguration crowd is necessarily confined in ways that the protest won't be, for safety reasons. No need to go through security screening checkpoints to march in the street. That doesn't affect who shows up to protest, but it will certainly affect the crowd size once the march is underway.

Last (but by no means least): It is Saturday. The weekend. One rejoinder to questions about Trump's turnout was that people had to work and so couldn't attend. On Saturday, that's less likely to be the case — particularly in a region that overwhelmingly backed Trump's opponent. That similar protests are scattered across the country, though, reinforces the broader point.

If Donald Trump weren't Donald Trump, though — if he weren't the candidate that was caught on tape casually discussing sexual assault and who, during his transition, made little effort to mend his relationship with the people who voted against him — the protest Saturday might not exist at all, much less see women and men coming out in force. The main driver of the anti-Trump protests, it's safe to say, is opposition to Trump.

The reassuring news is that it's exactly what circa-2012 Trump would have wanted to see happen.

Update: The WMATA reported 275,000 rides by 11 a.m. Saturday. On Friday, the figure at that point was 193,000.