Badwater Basin

Less than a hundred miles from the highest point in the contiguous United States, Badwater Basin in Death Valley holds the record as the lowest point in all of North America and is generally desolate save for the titular pool of salt water which is constantly evaporating. 

Smack in the middle of miles of treacherous salt flats, Badwater Basin is actually a fairly nondescript point a fair distance from the pool that gives it its name. The actual point sits at 282 feet below sea level at the end of a wooden pier that lets visitors come to the location without the danger of falling through the this layer of solid seeming ground into the mud beneath. A sign denotes the actual spot. 

The pool that gives the spot its name is a small body of water that sometimes seems as though it is not there when the level evaporates beneath the salty crust above. The salt content of the water makes it nearly toxic and gives the location its name. The cycle of evaporation in the low, hot site actually sees the fastest rate of evaporation in the nation. 

Low points aren't usually popular tourist sites, but when you get to claim to be the lowest point in in the great US of A, it doesn't matter if you are depressed or just a geography nut, its a site to see.