Gill is an unincorporated community and a U.S. Post Office in Weld County, Colorado, United States. The Gill Post Office has the ZIP Code 80624.A post office called Gill has been in operation since 1910. The community has the name of William H Gill, an early landowner.Gill is located at 40°27′14″N 104°32′30″W / 40.45389°N 104.54167°W / 40.45389; -104.54167.