How does competition from online platforms affect the organization, performance, and editorial choices of newspapers? What are the implications of these changes for the information voters are exposed to and for their political choices? We study these questions using the staggered introduction of Craigslist (CL)—the world’s largest online platform for classified advertising—across U.S. counties between 1995 and 2009. This setting allows us to separate the effect of competition for classified advertising from other changes brought about by the Internet, and to compare newspapers that relied more or less heavily on classified ads ex ante. We find that, following the entry of CL, local newspapers reliant on classified ads experienced a significant decline in the number of management and newsroom staff, including in the number of editors covering politics. These organizational changes led to a reduction in news coverage of politics and resulted in a decline in newspaper readership, particularly among readers with high political interest. Finally, we document that reduced exposure to local political news was associated with an increase in partisan voting and increased entry and success of ideologically extreme candidates in congressional elections. Taken together, our findings shed light on the determinants of the decline of print media and on its broader implications for democratic politics.