Senator Bernie Sanders visited the South Bronx yesterday evening, assembling more than 18,000 supporters and onlookers for a passionate rally in St. Mary's Park.

The crowd was a neighborhood spectacle. A security choke-point between Cypress and Beekman Avenues sent a throng of even the earliest attendees snaking east and then wrapping north for a mile, at least, along Jackson Avenue. A couple thousand slackers, distressed by the sight of such a long queue, poured into the park's eastern baseball field, which itself amounted to a massive picnic on the outskirts of attention.

Sanders represents a historic resurgence of the American Left.

Sanders visited the outfield to deliver brief and inspiring remarks ahead of his main stage address, which the candidate gave by nightfall. "We want a campaign finance system that is not corrupt, we want an economy that is not rigged, we want a criminal justice system that is not broken," he told supporters. "We are going to reinvest in the South Bronx and in communities all over this country."

The Sanders campaign's event programming began three hours after the advertised "doors open" time, with a chill setting in and clouds thickening overhead. The program featured remarks from a deep and diverse cast of prominent Sanders supporters, including the actor and activist Rosario Dawson and the filmmaker Spike Lee.

It wasn't the first time that a modern presidential figure has campaigned in the Bronx. Sanders' rally was, however, unprecedented in its turnout, a sign of his signature vitality among "grassroots" supporters.​ Sanders, the underdog of the 2016 Democratic presidential primary season, is riding a wave of such enthusiasm and favorable, statewide landslides in a make-or-break effort to close the delegate gap between him and Hillary Clinton.

In New York's presidential primary on April 19, Sen. Sanders will face off against Clinton, who represented New York for two terms in the U.S. Senate.

Clinton rallied at the Apollo Theater in Harlem the day before Sanders' rally in the South Bronx. In February, Clinton campaigned with Congressman Charlie Rangel and Mayor Bill de Blasio at the New York Public Library's Schomburg Center on Malcolm X Boulevard. These recent events represent a competitive effort from Clinton and Sanders to strengthen their support among black and brown voters nationwide.

With the Democratic National Convention now four months away, the Sanders and Clinton campaigns have sharpened their criticisms of one another. Barney Frank, the famously candid, now retired congressman from Massachusetts, recently challenged the credibility of his leftist colleague from Vermont. “Bernie Sanders has been in Congress for 25 years with little to show for it,” Frank told Slate, echoing persistent criticism that Sen. Sanders, a proud socialist, has brokered few meaningful compromises in his career as a U.S. senator.

Undoubtedly, Sanders insurgent popularity in the 2016 U.S. presidential election marks the peak of his political influence. President Barack Obama has done little to strengthen his party's national infrastructure and down-ticket odds in competitive Congressional races. (In Obama's two terms as president, Democrats have lost control of both the House and, more recently, the Senate.) For many, Sanders represents a historic resurgence of the American Left, previously marginalized by the centrist, compromise-driven politics that much of the Democratic Party's leadership has adopted for the past quarter century. On this front, Sanders at least stands a chance of shifting power to the American Left in a moment when, coincidentally, the American Right has succumbed to malaise and Donald Trump's madness.

"What this campaign is about is creating a political revolution," Sanders told his crowd at St. Mary's Park. "You are the heart and soul of this revolution."

While Sen. Sanders' rally in the Bronx did dwarf Clinton's Apollo turnout in size, the polling has long suggested that New York is a lock for Hillary Clinton, who stands nearly 30 points stronger than Sanders in the most recent polling out of New York. Sanders hopes to upset, as he did in Michigan. To advance his campaign into the summer, he needs to hit it out of the park.