51031 is a postalcode and its consensus geometry is derived from uszcta.
{"mz:is_ceased":0,"geom:latitude":42.801616,"wof:name":"51031","counts:names_total":0,"wof:placetype":"postalcode","mz:is_current":1,"wof:hierarchy":[{"continent_id":102191575,"country_id":85633793,"county_id":102086519,"locality_id":85944905,"postalcode_id":554726387,"region_id":85688713}],"mz:is_deprecated":0,"lbl:latitude":42.798547,"geom:area":0.06659,"geom:longitude":-96.179145,"wof:id":554726387,"counts:concordances_total":1,"geom:type":"Polygon","wof:lastmodified":1611184898,"wof:belongsto":[102191575,85633793,102086519,85944905,85688713],"wof:concordances":{"gp:id":"12780210"},"wof:repo":"whosonfirst-data-postalcode-us","src:geom":"uszcta","wof:country":"US","counts:names_preferred":0,"gp:parent_id":"12588346","geom:area_square_m":6.04134474690886E8,"wof:tags":[],"counts:names_variant":0,"wof:breaches":[],"edtf:inception":"uuuu","iso:country":"US","counts:names_languages":0,"geom:bbox":"-96.409914,42.648988,-96.016268,42.910005","wof:superseded_by":[],"wof:supersedes":[],"lbl:longitude":-96.186217,"wof:geomhash":"ade82d526c5abffec2481085680a3756","wof:parent_id":85944905,"wof:placetype_names":["postalcode"],"mz:hierarchy_label":1,"wof:placetype_id":470996387,"edtf:cessation":"uuuu","mz:postal_locality":"Le Mars"}