We estimate the effect of broadcast media outlets revealing information about incumbent performance on electoral accountability in Mexico. Focusing on malfeasance by municipal mayors, we study federal grants earmarked for infrastructure projects targeting the poor, and leverage two sources of plausibly exogenous variation. First, we exploit variation in the timing of the release of municipal audit reports around elections. Second, and moving beyond existing studies, we compare neighboring electoral precincts on the boundaries of media stations' coverage areas to isolate the effects of an additional broadcast media station. We find that voters punish the party of malfeasant mayors, but only in precincts covered by local media stations, which emit from within the precinct’s municipality. An additional local radio or television station reduces the vote share of an incumbent political party revealed to be either corrupt or neglectful of the poor by around 1 percentage point. The effect of a local media station is larger when local media stations principally serve the market inside their municipality. In contrast, while we find no evidence that non-local media stations contribute to the electoral sanctioning of malfeasant mayors, our results indicate that non-local media crowds out the sanctioning effects of local media. Our findings thus indicate that electoral accountability requires that the media market structure provides media stations with incentives to supply politically-relevant information to their audiences.