Along the Arizona-Sonora border, the U.S. Consulate in Nogales has quietly drawn a line around daylight itself — restricting government movement to essential hours only in response to a threat that remains, by official account, unnamed. The gap between American concern and Mexican reassurance speaks to something older than any single incident: the chronic ambiguity of life on a border where risk is real but rarely fully legible. Americans in the area are left to navigate not a declared danger, but the shadow of one.