21029 is a postalcode and its consensus geometry is derived from uszcta.
{"mz:is_ceased":0,"geom:latitude":39.205594,"wof:name":"21029","counts:names_total":0,"wof:placetype":"postalcode","mz:is_current":1,"wof:hierarchy":[{"continent_id":102191575,"country_id":85633793,"county_id":102084263,"postalcode_id":554707131,"region_id":85688501}],"mz:is_deprecated":0,"lbl:latitude":39.213616,"geom:area":0.004363,"geom:longitude":-76.952963,"wof:id":554707131,"counts:concordances_total":1,"geom:type":"MultiPolygon","wof:lastmodified":1611183152,"wof:belongsto":[102191575,85633793,102084263,85688501],"wof:concordances":{"gp:id":"12766416"},"wof:repo":"whosonfirst-data-postalcode-us","src:geom":"uszcta","wof:country":"US","counts:names_preferred":0,"gp:parent_id":"12588689","geom:area_square_m":4.1807575643351E7,"wof:tags":[],"counts:names_variant":0,"wof:breaches":[],"edtf:inception":"uuuu","iso:country":"US","counts:names_languages":0,"geom:bbox":"-77.012165,39.160491,-76.889473,39.248149","wof:superseded_by":[],"wof:supersedes":[],"lbl:longitude":-76.959448,"wof:geomhash":"a685f541c53891caf5a9d3d302068fc8","wof:parent_id":102084263,"wof:placetype_names":["postalcode"],"mz:hierarchy_label":1,"wof:placetype_id":470996387,"edtf:cessation":"uuuu","mz:postal_locality":"Clarksville"}