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American Community Survey (ACS) Data (view source)
Revision as of 20:16, 11 February 2021
, 20:16, 11 February 2021→Working with the API
The API doesn't seem to require a key, but you can request one from https://api.census.gov/.
The data contains null values, as well as values that indicate error codes (-999999999,-888888888,-666666666,-555555555,-222222222, and others. See https://www.census.gov/data/developers/data-sets/acs-1year/notes-on-acs-estimate-and-annotation-values.html. Generally, it appears that all negative and null values should can be striped. Every field is string quoted including error codes, except for nulls.
The API uses improper URL encoding (or more accurately, doesn't use URL encoding), so most methods for auto-populating URL parameters in scripting languages will not function correctly. Build URLs manually.
The API returns improper JSON. Essentially, it just encodes a flat data structure into JSON syntax one line at a time, and completely ignores the structure of the data (and so much of the point of encoding it in JSON!). However, the first (zeroth) column is the requested geography name, so multiple pulls can be joined using that. And the first (zeroth) row is a valid set of column headers. Also, the nulls are valid JSON encodings. This, and the strong quoting, which makes using a JSON handler likely worthwhile (otherwise, one would just . An alternative is to strip the JSON tags and treat it the data as a badly encoded CSV, which it is).
To request a group ask for '''group(B06009)''' where you would normally request a field like '''B06011_001E'''. Programmers can rely on groups and fields being identifiable from the "_" and the string length (\d{5}\w{0,1}_\d{3}\w{1}).
