21550 is a postalcode and its consensus geometry is derived from uszcta.
{"mz:is_ceased":0,"geom:latitude":39.389031,"wof:name":"21550","counts:names_total":0,"wof:placetype":"postalcode","mz:is_current":1,"wof:hierarchy":[{"continent_id":102191575,"country_id":85633793,"county_id":102082181,"locality_id":85949215,"postalcode_id":554707331,"region_id":85688501}],"mz:is_deprecated":0,"lbl:latitude":39.389381,"mz:postal_locality_alt":["Mountain Lake Pk","Deer Park","Mc Henry","Crellin"],"geom:area":0.05579,"geom:longitude":-79.3909,"wof:id":554707331,"counts:concordances_total":1,"geom:type":"Polygon","wof:lastmodified":1611183130,"wof:belongsto":[102191575,85633793,102082181,85949215,85688501],"wof:concordances":{"gp:id":"12766590"},"wof:repo":"whosonfirst-data-postalcode-us","src:geom":"uszcta","wof:country":"US","counts:names_preferred":0,"gp:parent_id":"12588687","geom:area_square_m":5.33155141537749E8,"wof:tags":[],"counts:names_variant":0,"wof:breaches":[],"edtf:inception":"uuuu","iso:country":"US","counts:names_languages":0,"geom:bbox":"-79.487651,39.202107,-79.231907,39.557125","wof:superseded_by":[],"wof:supersedes":[],"lbl:longitude":-79.390745,"wof:geomhash":"0e80c54e4ac5f1a9edbd02e46b34b2fa","wof:parent_id":85949215,"wof:placetype_names":["postalcode"],"mz:hierarchy_label":1,"wof:placetype_id":470996387,"edtf:cessation":"uuuu","mz:postal_locality":"Oakland"}