21239 is a postalcode and its consensus geometry is derived from uszcta.
{"mz:is_ceased":0,"geom:latitude":39.36646,"wof:name":"21239","counts:names_total":0,"wof:placetype":"postalcode","mz:is_current":1,"wof:hierarchy":[{"continent_id":102191575,"country_id":85633793,"county_id":102081589,"locality_id":85949461,"postalcode_id":554707283,"region_id":85688501}],"mz:is_deprecated":0,"lbl:latitude":39.367099,"geom:area":8.76E-4,"geom:longitude":-76.587333,"wof:id":554707283,"counts:concordances_total":1,"geom:type":"Polygon","wof:lastmodified":1611183157,"wof:belongsto":[102191575,85633793,102081589,85949461,85688501],"wof:concordances":{"gp:id":"12766530"},"wof:repo":"whosonfirst-data-postalcode-us","src:geom":"uszcta","wof:country":"US","counts:names_preferred":0,"geom:area_square_m":8373832.488184,"wof:tags":[],"counts:names_variant":0,"wof:breaches":[],"edtf:inception":"uuuu","iso:country":"US","counts:names_languages":0,"geom:bbox":"-76.600303,39.340661,-76.569997,39.390848","wof:superseded_by":[],"wof:supersedes":[],"lbl:longitude":-76.589171,"wof:geomhash":"f349f7cc6339da79597c82669f62940f","wof:parent_id":85949461,"wof:placetype_names":["postalcode"],"mz:hierarchy_label":1,"wof:placetype_id":470996387,"edtf:cessation":"uuuu","mz:postal_locality":"Baltimore"}