Congressional members and staff on September 23, 2020

LegiStorm tracks biographical data for both members and staffers in real time.

Member data is 100 percent complete across each of these categories, while staffer data completeness varies. Gender data for staffers is almost totally complete, whereas religion data is much more spotty.

Staffers working for an undetermined party includes those in nonpartisan and bipartisan positions, staffers who have a history working for members of multiple parties, and a limited number of former staffers with incomplete party data.

Age was sometimes determined based on information provided by the person involved, often via social media, or through some other reference source. Or if an age was unavailable, LegiStorm also calculated approximate age based on the year staffers completed an undergraduate degree, assuming they were 22 at the time. These estimated ages are never listed on LegiStorm's site for individual staffers, but are only used in aggregate statistical numbers.

The race of members of Congress is usually well publicized and little in dispute. For the race of staffers, LegiStorm never identifies the race of individual staffers. However, to create aggregate numbers, we use visual identification and other cues such as name, languages spoken and involvement in racial or cultural organizations, as well as an occasional public declaration by the staffer.

For religion, data is widely available for members, although it's only available for a relatively small number of staff. LegiStorm created broader categories from our more specific data. The Christian (Other) category includes Christian denominations that do not fall under the Protestant or Catholic umbrellas and the staffers and members who are Christian but have not specified a particular denomination. LegiStorm separately tracks Mormonism from other Christian categories because of its higher numbers among both members and staff.