You may have noticed that the polls happening between the Democratic Pref polls are more like trivia questions. I like trivia. I put this one up to force myself to find the answer to the question.
It is a tricky one. The end of the Delaware River and the beginning of the Delaware Bay seems to be a moving target. I couldn’t find anything definitive, but if we used the “the salt line” as a starting point, we get the river ending and the bay starting just above the Christiana River at RM71. I guess RM means “River Mile” with the mouth of the Delaware Bay being (ironically for our purposes) RM0.0. According to the DRBC’s RM standard for measuring the length of the Delaware River, there is no bay – IT IS ALL RIVER! Incidentally, the Delaware Memorial Bridge is RM68.7, so people who picked the bridge were pretty close.
Anyhoo… RM71 is the “median monthly salt front” according to the Delaware River Basin Commission. The DRBC keeps an eye on the salt line because salt is bad for commercial operations along the river. When fresh water flow goes down (during a drought for example) the salt line creeps north. If it creeps too far north, the DRBC has ENORMOUS reservoirs in New York and Pennsylvania from which it releases water to flush back the salt. It is one of those millions of invisible ways governments make your life better without you ever knowing or giving a flying fuck about it.
Bonus: The Delaware is the 33rd largest river in the United States in terms of flow, but the nation’s #1 river in daily volume of tonnage, so says wikipedia. I don’t know how that can be true, but Suck it Mississippi!