Ads keep the MarioWiki independent and free :)
The Fog Horn is an item in Mario is Missing! It is part of the warning system for fog on the Golden Gate Bridge. It is stolen by a group of Koopa Troopas that attack San Francisco, causing the entire bridge to close. Luigi later comes across it on a Koopa Troopa wandering through the city, and takes it for himself. He then brings it to various San Franciscans while attempting to pinpoint where it belongs; everyone that he speaks to points him in the direction of the bridge while also providing him with additional information, such as how it is 260 feet above the San Francisco Bay (despite how the bridge is actually 220 feet above water from bridge itself and 500 feet above land from the top of the tower). Armed with this knowledge, Luigi is able to return the Fog Horn to the Golden Gate Bridge through its information booth, and he receives $2240 as a reward for doing so alongside a $3200 if the Fog Horn is returned first.