The New York Democratic primary has taken on an improbable degree of significance this year. The state leans toward presidential front-runner Hillary Clinton — a former U.S. senator from New York — but polls have been narrowing, and challenger Bernie Sanders is currently riding an impressive six-state winning streak. The most recent notch in his belt was Wisconsin, where he defeated Clinton by a double-digit margin on Tuesday.

New York’s April 19 primary presents Sanders with another opportunity to beat expectations, or for Clinton to erect a firewall against him. Both campaigns are reportedly looking for clues from another fierce intra-Democratic battle that took place in New York: the 2014 gubernatorial primary between incumbent Andrew Cuomo and progressive challenger Zephyr Teachout.

Teachout — a law professor, progressive activist and online organizer for Howard Dean’s 2004 presidential campaign — first challenged Cuomo for the nomination of the Working Families Party, which usually lists Democrats on its ballot line. When Cuomo triumphed at the WFP convention, Teachout sought the Democratic nomination instead.

The ideological divisions between Cuomo and Teachout were similar to the ones that now define the Democrats’ 2016 presidential primary. Cuomo, who has longstanding ties to the Clintons, was the candidate of the party’s center. Teachout challenged him from the left, citing what she described as Cuomo’s break with “traditional Democratic values” such as greater investment in public education.

Teachout lost to Cuomo, but surpassed expectations by winning nearly one-third of the vote. She’s now running for Congress upstate, and the New Republic has described her as part of “Bernie’s army,” the small group of downticket candidates who are echoing the Sanders message in their campaigns. Cuomo has endorsed Clinton.

The 2014 electoral map holds some lessons for Clinton and Sanders as they square off in this year’s presidential primary. Teachout performed best in many of New York’s whiter, more rural districts; Sanders has followed the same pattern nationally. Similarly, Clinton has swept states where black voters make up the biggest chunk  of the Democratic electorate, and Cuomo’s biggest wins were concentrated downstate in the dense, urbanized, ethnically diverse counties of New York City.

Sanders enjoys some benefits that Teachout did not: He has stronger name recognition and a formidable fundraising operation. The money may be particularly significant, given how much Cuomo spent in his effort to make a strong showing against Teachout. A Washington Post analysis found that the incumbent governor’s campaign spent $60 for each vote he earned, whereas each vote for his opponent cost barely more than $1.50.

But major hurdles remain for Sanders, particularly if New York’s 2016 electoral map at all resembles that of the 2014 primary. The counties where Cuomo did best are the ones where the most votes are; in Bronx County, which he won by nearly 70 points, more than 47,000 votes were cast. Teachout did better in the more sparsely populated counties like Columbia County, where 2,297 votes were cast and she won by a 55-point margin.

Furthermore, there may not be enough truly competitive counties for Sanders to eat away at those margins. Barely 4 percent of all the votes cast in 2014 were in counties where either Teachout or Cuomo won by a single-digit margin. The remaining counties were blowouts for one candidate or the other.

The 2014 map suggests that Sanders is likely to win most or all of the counties bordering Vermont, the state he represents in the U.S. Senate. But he’s also likely to lose his birthplace: Kings County, also known as Brooklyn, went for Cuomo by 40 points in 2014. 

The New York map demonstrates why, despite Sanders’ recent wins, the architecture of the race still strongly favors Clinton.