Use {{location|US}} to tag expeditions that took place in the United States of America. It will add Category:Expeditions in the United States of America to the expedition.
You may also tag the state or even the county or county equivalent that the expedition took place. For the states, use ISO 3166-2 abbreviations. For districts, use the hierarchical administrative subdivision codes which can be found here.
If the category link appears red, do not worry and create the category. Make sure that it is included in the appropriate parent category, for instance, Category:Expeditions in Queens County, New York is a subcategory of Category:Expeditions in New York, which is a subcategory of Category:Expeditions in the United States of America. The subcategories should be sorted in by their respective code.
Examples
{{location|US}}: the United States of America{{location|US|NY}}: New York{{location|US|NY|QU}}: Queens County, New York{{location|US|LA|SC}}: St. Charles Parish, Louisiana{{location|US|AK|AE}}: Aleutians East Borough, Alaska{{location|US|AK|AW}}: the Aleutians West Census Area, Alaska{{location|US|AK|JU}}: Juneau, Alaska{{location|US|VA|RE}}: Roanoke County, Virginia{{location|US|VA|RO}}: Roanoke, Virginia
