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As of this writing, the Iowa Democratic presidential caucus is still too close to call. Bernie Sanders and Hillary Clinton are separated by only a few tenths of a percentage point, and the winner may not be known for several more hours.

But before the final tally is known, it's worth reflecting on what, for the Sanders camp, has been a genuinely amazing political achievement. Even if Bernie Sanders doesn't ultimately win the Democratic nomination, what he did in Iowa—pose a real, sustained threat to Clinton, one of the most formidable politicians of her generation and the hands-down choice of the party's establishment— should cement his place in history. As Slate's Jamelle Bouie put it, Sanders is "the first socialist in a century to build a genuine mass movement in American party politics."

It's especially impressive when you look back at how Sanders got started.

Here is a photo of the day in April 2015 when Sanders announced his candidacy for president. As shown in this YouTube video, it was an informal press conference outside the U.S. Capitol building, attended by a few dozen photographers and reporters.

And here is a photo from last weekend, of one of Sanders' final rallies before the Iowa caucuses.

Sanders at the University of Iowa.
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What a difference nine months makes.