Replication Data for: Local News and National Politics

The level of journalistic resources dedicated to coverage of local politics is in a long term decline in the US news media, with readership shifting to national outlets. We investigate whether this trend is demand- or supply-driven, exploiting a recent wave of local television station acquisitions by a conglomerate owner. Using extensive data on local news programming and viewership, we find that the ownership change led to 1) substantial increases in coverage of national politics at the expense of local politics, 2) a significant rightward shift in the ideological slant of coverage and 3) a small decrease in viewership, all relative to the changes at other news programs airing in the same media markets. These results suggest a substantial supply-side role in the trends toward nationalization and polarization of politics news, with negative implications for accountability of local elected officials and mass polarization.