I am working on a dataset that comes from survey results. The only location identifying information we have from those who took the survey is the first three digits of the U.S. zip code.
How detailed of location information does this give?
The United States Postal Service maintains ZIP Code boundaries and ZIP3 boundaries. ZIP3's are an amalgamation of ZIP codes that contain those first 3 numbers. There are plenty of ZIP code boundaries available online, dissolving those on the first 3 digits gives you ZIP3 boundaries.
The location is less detailed than ZIP code boundaries, because it is a combination of the finer level ZIP codes.