Suggesting tiles by region with finer granularity than country

[ For context around Suggested Tiles, please read http://ed.agadak.net/2015/04/whys-and-hows-of-suggested-tiles ]

So far Tiles have been served to users at a country level. This is good enough for content that should reach a broad audience, but this also prevents us from providing highly relevant content to smaller audiences.

For example, if we want to suggest a Mozilla recruiting tile to developers for our San Francisco / Mountain View offices, right now we would have to show it to all developers in the US. This would probably lead to disappointment for people interested in working remotely from other states to only find out the position is local.

We're planning on using finer granularity, and we're curious to hear people's thoughts on what's the appropriate level as there's potential privacy concerns.

One proposal is state level for USA. The smallest state by population is around 600k people for Wyoming [1]. There's 50 states, but that might not be the right granularity either as large states like California could be split into northern and southern audiences. Another issue is metropolitan areas near borders such as New York can span several portions of multiple states.

Another proposal is Designated Market Area (DMA), which I believe was created to address the above states concerns and has already been widely used. There's 210 of these with sizes that vary from very large nearing 20m for New York [2] down to Glendive, MT with 10k.

For either proposal, we don't need to use all states or DMAs. For example, if we determine a minimum audience size of 1m, we can use some of the larger ones and skip the smaller ones.

Do people have suggestions on what's the appropriate granularity?

Ed Lee

[1] http://en.wikipedia.org/wiki/List_of_U.S._states_and_territories_by_population
[2] http://www.tvb.org/markets_stations#!id=137&type=market