Query Overpass Turbo for postal code boundaries

Question

I'm looking to query Overpass Turbo for postal code boundaries, specifically all within the USA. Here's what I found so far and where I'm stymied:

This query for postal code boundaries in Liepzig works:

area[name="Leipzig"][admin_level=6][boundary=administrative]->.myarea;
rel(area.myarea)["boundary"="postal_code"];
out geom;

This query for boundaries of the State of Oregon works:

area[name="Oregon"][admin_level=4][boundary=administrative]->.myarea;
rel(pivot.myarea);
out geom;

But this query for postal code boundaries inside the State of Oregon does not:

area[name="Oregon"][admin_level=4][boundary=administrative]->.myarea;
rel(area.myarea)["boundary"="postal_code"];
out geom;

Thoughts on why this last query doesn't work while the first two do?

Answer 1

You can only get out of Openstreetmap what others have put into the database.

If you look at https://taginfo.openstreetmap.org/tags/boundary=postal_code#map, you will see that boundaries of type postal_code are mostly used in Germany, but only few outside.

Address information is mainly stored using the key addr:postcode, as you see at https://taginfo.openstreetmap.org/keys/addr:postcode#map, as well as the key postal_code https://taginfo.openstreetmap.org/keys/postal_code#map. So you have to query for those, and build boundary polygons from that yourself.

You will probably run into timeout problems with Overpass, so think of downloading http://download.geofabrik.de/north-america/us/oregon-latest.osm.pbf and filter that locally. Or take a look at Sources for US Zip Code Boundaries? or https://www.census.gov/geo/maps-data/data/cbf/cbf_zcta.html