Women remain underrepresented in most legislative bodies around the World. In this paper, we investigate if the election of a woman for office spearheads female representation. We rely on administrative data and close elections in Denmark from 1993 to 2017 to estimate the difference between marginally electing an additional woman compared to electing an additional man. Specifically, we focus on local elections, where a woman marginally wins a seat over a man competing for the same seat. Local elections in Denmark are proportional and most parties run on open lists where the number of personal votes alone decides who gets the seats that the party wins in the elections. Within clusters of each municipality, party list, and election year, this creates a number of close elections and in some of these, a woman marginally beats a man or not. We use this as a source of random variation in the share of elected women both within each party list and within each municipality board to estimate effects of increased female representation. Our findings show that a woman marginally elected increases the share of women within the same party in the succeeding election. The effect is driven by incumbent women being more likely to rerun, while an additional woman reduces the share of new female candidates in the future candidate pool. Other parties within the municipality also increase their share of women in the subsequent election.