54840 is a postalcode and its consensus geometry is derived from uszcta.
{"mz:is_ceased":0,"geom:latitude":45.756239,"wof:name":"54840","counts:names_total":0,"wof:placetype":"postalcode","mz:is_current":1,"wof:hierarchy":[{"continent_id":102191575,"country_id":85633793,"county_id":102081835,"localadmin_id":404492979,"postalcode_id":554728723,"region_id":85688517}],"mz:is_deprecated":0,"lbl:latitude":45.751262,"mz:postal_locality_alt":["Trego"],"geom:area":0.079195,"geom:longitude":-92.689055,"wof:id":554728723,"counts:concordances_total":1,"geom:type":"Polygon","wof:lastmodified":1611185070,"wof:belongsto":[102191575,85633793,102081835,404492979,85688517],"wof:concordances":{"gp:id":"12781554"},"wof:repo":"whosonfirst-data-postalcode-us","src:geom":"uszcta","wof:country":"US","counts:names_preferred":0,"gp:parent_id":"12590540","geom:area_square_m":6.8323801571655E8,"wof:tags":[],"counts:names_variant":0,"wof:breaches":[],"edtf:inception":"uuuu","iso:country":"US","counts:names_languages":0,"geom:bbox":"-92.889433,45.556696,-92.510112,45.951585","wof:superseded_by":[],"wof:supersedes":[],"lbl:longitude":-92.692383,"wof:geomhash":"1b99b1ff8764b856ee16af885e039911","wof:parent_id":404492979,"wof:placetype_names":["postalcode"],"mz:hierarchy_label":1,"wof:placetype_id":470996387,"edtf:cessation":"uuuu","mz:postal_locality":"Grantsburg"}