My interests in ballot questions and map-making continue to collide. Below is a map of 2016 advertising data on ballot questions. The map plots ad totals for the 2015-16 election cycle at the level of the media market, which consist of collections of counties. There are over 3,000 counties in the United States, but 210 media markets. Markets often spill over state boundaries. See this map, which allows you to click through to see which counties align with which markets. The map below is for ads airing on broadcast television stations (excluding local cable, radio, and digital/online ads).
Lots of ads air in the western states, in line with my earlier post on where ballot questions are more prominent.