Sources and methods
How we know what we know.
165 years of U.S. election data. This is what we cover, how we compute it, and where we are honest about the limits. Pick the path that matches how you work.
Historical floor
1868
Geographic scope
8M+
Reference depth
7 pages
Where to start
Pick the path that matches how you work
Methodology pages are usually read under deadline. These three paths surface the sub-pages each audience tends to reach for first.
I'm a campaign professional
You need numbers you can stake a strategy on. Start with how we forecast races and how we grade candidates.
I'm a journalist
You need to cite us without getting burned. Start with the source inventory and the citation formats.
I'm a researcher
You need reproducible methods and honest limitations. Start with margins, data provenance, and block-level disaggregation.
Every methodology topic
Browse the full reference
Each sub-page is a focused explanation with worked examples, interactive components where useful, and honest limitations.
Contact
Questions we didn't answer
Researchers, librarians, journalists, and campaign teams can reach out for institutional access, bulk data requests, or source clarification.
Methodology support