Where can I find data on US party affiliations, broken down geographically?

I'd like to do some statistical analysis on party affiliations within states, broken down geographically.

Here's the kicker: everything I've seen as a data source is never more granular than the voting district.

I want to do some trending using below that level, possibly city blocks or rural roads.

I'd like to try identifying shifts within districts, over the last several elections.

I'd also like to try to do some "what-if" scenarios based on drawing districts differently.

Ultimately, I'd like to get a web application set up to allow others to do similar "what-if" scenarios.

So, does anyone know any source for data at that level of granularity? Preferably open data not encumbered by usage terms.

Thanks in advance.

  • 4
    Most likely this data is not publicly available. Public election results will not be broken down further than precinct. To get more granular party affiliation (at least in Michigan for sure), you would need data directly from the Democratic Party and Republican Party, as they keep their lists of party members. Folks in Michigan do not register with the State as a party member, so the State would not have this information. And I imagine neither party will hand over the data carte blanche. Nov 9, 2020 at 18:28
  • 1
    Hopefully this data is not publicly available. Precincts are small enough. Nov 9, 2020 at 22:31

1 Answer 1


Data is easily available at the county level in most states, the New England town level in some New England states, the Parish level in Louisiana, the Ward level in D.C., and the State House district in Alaska. Media outlets and state election administrators (usually but not always a state's Secretary of State) have this information available online and some county level election administrators also have online and precinct level data.

Most states have publicly available data down to the precinct level, but that information is frequently not available online (especially in more rural areas) and often has to be gathered laboriously on a county by county basis in abut 3500 election administration divisions.

Everyone in a precinct usually has exactly the same ballot questions and candidates, but sometimes multiple precincts have exactly the same ballot questions and candidates. A precinct typically has hundreds to several thousand residents, and almost never more than 10,000 to 20,000 residents. In NYC that might be a single block. In most places, it would be portion of a neighborhood or a full smaller neighborhood. Some precincts have only dozens of residents. My precinct in an urban residential area in Denver, Colorado is about a dozen blocks and would be fairly typical. In most reasonably densely populated states, the precinct is the base level of major political party organization with a precinct committee person or officer in every precinct where the party has members.

Voter turnout of 60%-70% of census population would typically be an upper limit of votes cast, and the typical percentage would be significantly lower.

In states that have partisan voter registration and voter participation information, it is available at a more fine grained level (to the level of the individual voter registration address) but usually only on a paid subscription basis.

The smallest unit used to draw legislative district boundaries is a "census block" since this is the smallest unit of census reporting and redistricting must be based upon census populations. The number of blocks in the United States, including Puerto Rico, for the 2010 Census was 11,155,486 (an average of about 300 people each). Census data at the block level is easily obtained as a public record if not online in downloadable files, a least in a public library reference that is a few years out of date.

"Party affiliation" is an ill defined concept with multiple operational definitions. One is to look at voter registration data in states that have partisan voter registration. Another is to look at election outcomes in fairly competitive contested partisan statewide elections to provide comparability between different parts of a state. It is also possible to sort campaign contribution data by partisan affiliation of a donee and zip code.

  • Probably a lot of precincts would have the exact same ballot, no? The lowest division I can think of would be city wards, which in my city look like they include about a dozen precincts. Although I guess those could be split up by US and state house districts. Nov 10, 2020 at 19:56
  • @AzorAhai-him- There is lots of state to state variation in how election administration geographic units are named and organized. Precincts almost never have multiple different ballots, but beyond that, practice varies.
    – ohwilleke
    Nov 10, 2020 at 20:25

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