This is a list of the highest bridges in the United States by height over land or water. Height in this list refers to the distance from the bridge deck to the lowest point on the land, or the water surface, directly below. A bridge's deck height is greater than its clearance below, which is measured from the bottom of the deck structure, with the difference being equal to the thickness of the deck structure at the point with the greatest clearance below. Official figures for a bridge's height are often provided only for the clearance below, so those figures may be used instead of actual deck height measurements. For bridges that span tidal water, the clearance below is measured at the average high water level.