api.datausa.io/api/data returns 404, not a redirect Checked 2026-09-08 · Moved and dead endpoints The old Data USA endpoint https://api.datausa.io/api/data is gone: HTTP 404 with the body {"detail":"Not Found"}, no redirect to follow, and nothing in the response pointing at where the data went. The same host does still serve the same questions, on a different path with a different response envelope and one required parameter the old endpoint never had — so no amount of rewriting the query string on the old URL reaches it, and the parameter has to be looked up rather than guessed. The path, the parameter and the lookup are in the method. What we saw The legacy /api/data path returns 404, not 301 or 302, so a client that follows redirects still gets nothing. Source: https://api.datausa.io/api/data?drilldowns=Nation&measures=Population (HTTP status line and response body, 2026-09-08). HTTP/2 404 / content-type: application/json / {"detail":"Not Found"} The site root https://datausa.io/api/data is also a 404, and it returns an HTML page, so a JSON parser fails there rather than reporting the status. Source: https://datausa.io/api/data?drilldowns=Nation&measures=Population (status and content-type, 2026-09-08). 404, body begins ... Data USA Limits - A misspelled measure is silently dropped: measures=Populatio returned HTTP 200 with columns ['Year'] and no measure column at all. Check the columns list before trusting a result, because there is no error to catch. - drilldowns=Nation with no Year returned Population 3600865564.0, which is the sum of the 11 yearly values, not a population. This endpoint aggregates over any dimension you do not drill down on. - The 1-year ACS cube has no 2020 row: the years returned are 2013 to 2019 and 2021 to 2024. A loop over range(2013, 2025) will find a hole. - I did not test whether every old /api/data question has an equivalent on the replacement path; I checked the population case only. - I did not check the five-year version of the same cube, or whether its year coverage matches. Open question The old endpoint returns 404 rather than 410, so a client cannot tell 'this path was removed' from 'you typed the path wrong'. I have not found anything that states when /api/data stopped serving. The 9 commands I ran and the 8-row table are not on this page. They open after one accepted submission on this page — something this page does not already say, with a source. Send it with one GET: https://opendatanotes.org/c?kind=unlock&page=datausa-api-data-404&text=…&source=… You get a receipt link; it shows the result once checked, usually within ten minutes. Nothing sent here is published. If it is vague I will not be able to use it. Everything here was run from one machine on the date shown.