On July 13, 2013, in the hours after a nearly all-white jury acquitted George Zimmerman of all charges in connection with the shooting death of an unarmed black teen named Trayvon Martin, a trio of friends tried to convey their disappointment, disgust and fear in conversations with the people around them -- and online.

[Zimmerman found not guilty]

One of those women, Alicia Garza, posted a note on Facebook that ended with an idea: It was time to organize and ensure "that black lives matter." The hashtag her friend, Patrisse Cullors, attached (#BlackLivesMatter) and the effort launched by both women and a third friend, Opal Tometi, caught fire. The women, professional organizers working for various groups by day, began by night to construct the scaffolding of what the New York Times magazine would in May call the 21st Century's first civil rights movement.

That same story describes the movement's origins a little differently with a different moment, a different place and two different activists committed to the same cause.

But then, and now, this much is clear: Black Lives Matter has evolved well beyond a hashtag attached to sometimes-smart and often-snarky posts about policing, jailing and racial disparities in the United States. Black Lives Matter, it would seem, has evolved into a social movement with political aims, policy demands and a disparate set of individuals motivated to push those issues into the 2016 campaign.

The short version of the journey of Black Lives Matter from hashtag to IRL political movement is this: Once galvanized by a slogan that happened to fit well within the confines of Twitter, people took to the streets in New York, in Ferguson, Mo., in Cleveland, in North Charleston, S.C., and in Baltimore when unarmed black men and an actual child were gravely injured by police.

Some were there to loudly but peacefully protest just how common policing for profit, presumed guilt and aggressive, sometimes dangerous and deadly police tactics in black communities had become. Some saw it as a moment to pour out their long-fomenting anger about economic and social conditions. And some subset of the latter set things on fire, broke windows and looted in Ferguson and Baltimore. Several Black Lives Matter activists have condemned that activity and described looters as individuals unaffiliated with the movement.


Police in riot gear line up near the scene of Monday's riots ahead of a 10 p.m. curfew Wednesday, April 29, 2015, in Baltimore. The curfew was imposed after unrest in Baltimore over the death of Freddie Gray while in police custody. (AP Photo/David Goldman)

Today, the collection of national and local organizations working under the banner of Black Lives Matter is showing all the signs -- and struggles -- of a nascent political movement.

There are internal fights and both productive and unproductive disagreements about who the movement's leaders are, whether leaders are needed, what the movement should do now and whether coordination itself is a good thing. There are disputes about tactics, but also some agreements about how to move forward. The ideas behind the movement do have enough traction that a Twitter-generated map of the hashtag's use circumnavigates the globe. The hashtag's use alone is something to behold.

And in what might be the surest sign yet that a real and functioning movement has been birthed, there are documents and reports detailing the many ways in which Black Lives Matter activists and protest actions have been -- and perhaps remain -- the subject of government monitoring.

But what has become notable, perhaps even deeply telling, is the way in which presidential candidates and even some voters have reacted to a group of young, mostly but not exclusively black activists trying to find candidates to champion their cause. (See the video above.)

So far, that effort has focused largely on Democratic candidates for the presidency -- Hillary Rodham Clinton, Martin O'Malley and Bernie Sanders. They crashed Netroots Nation a month ago, forcing O'Malley and Sanders into uncomfortable situations. They have focused intently on Sanders. And they even threatened to interrupt a Clinton campaign event last week -- a flap that ended with Clinton meeting with leaders of the group.

Activists from Black Lives Matter and other groups interrupted Democratic presidential candidates Bernie Sanders and Martin O'Malley during a Netroots Nation event in Phoenix. (Sarah Parnass/The Washington Post)

The group's critics on the left argue that Clinton, O'Malley and Sanders are the only influential political allies the group has, and that the assertive, youthful energy Black Lives Matter has brought to the Democratic candidates' campaign events should be redirected toward Republicans. (On at least one occasion this month, they have.) Democrats, these people say, have been the political friends of black Americans -- at least since the 1960s. Why can't Black Lives Matter activists make their demands in private and focus on amassing support for pragmatic policy ideas that white Americans can support?

On the right, more than one candidate and his or her supporters have expressed a different set of critiques. To several Republican candidates, Black Lives Matter activists are fundamentally focused on the wrong issues, the wrong things. Instead of calling for police reforms, young black Americans need to embrace the discipline of work and safety that comes with law-abiding life and avoid public strife. Black parents need to better monitor their children, their souls, their character. And police officers, a brave and public-service-minded lot, should plow ahead in the work of enforcing law and maintaining order. And, yes, as former Florida governor Jeb Bush, businessman Donald Trump and Sen. Ted Cruz (R-Tex.) have acknowledged, there have been some incidents of possible police misconduct caught on tape that are worthy of official inquires.

At this point, Black Lives Matter protesters do have some inside-politics-type results to boast.

In the months since Black Lives Matter protesters began showing up and sometimes taking over campaign events, holding private and private-but-on-tape meetings with candidates, Clinton, Sanders and O'Malley have made some adjustments in the way they talk about policing, race and criminal justice reforms.

O'Malley and Sanders have released relatively detailed policy proposals to deal with disparities in the criminal justice system and the way that police and prosecutors do their work. Sanders has added a campaign staffer whose resume happens to include Black Lives Matter activism. But, he has also balked at suggestions that his campaign has apologized to Black Lives Matter Activists for, well, anything.

And Clinton -- who dedicated one of her earliest campaign speeches to ending mass incarceration without acknowledging it was a policy for which she lobbied that rapidly expanded the prison population -- has hinted that she has her own policy proposal in the works.

For now, Clinton, the Democratic front-runner, has conceded at least this. When Black Lives Matter protesters show up, she cannot simply walk away.