Preserved In A Name

That’s a picture of the Macombs* Dam Bridge over the Harlem River. It’s 123 years old and has two main spans: a swing bridge over the river (that rotates to clear the channel, if needed) and a truss over the low-lying land on the Bronx shore (occupied for a long time by railroad tracks).

“Dam Bridge” is an odd enough name** that it deserves explanation. As is reasonably well-known and I’ve discussed before, the East River is a tidal strait rather than a river. The Harlem River, which connects the East and Hudson Rivers (and thereby makes Manhattan an island) is also a tidal strait. There are a bunch of differences between straits and rivers, once of the biggest being that you can build a dam across a strait without having the water back up and create a pool of some kind. Damming the Harlem River (or the East River, or that matter) stops the current entirely. In 1814, Robert Macomb did just that, damming the Harlem River to use the tidal flow to power a mill. Eventually the dam was demolished, but the name stuck for that spot on the river.

* A minor etymological note: the dam was built by Mr. Macomb, so the dam and bridge should be spelled “Macomb’s.” The possessive apostrophe got swallowed, in the same manner that the river abutting the seventeenth-century farm of Jonas Bronck became Bronck’s River and then the Bronx River, and eventually gave its name to the surrounding area. I don’t know if that kind of thing happens everywhere, but the classic New York accent lends itself to swallowing terminal consonants.

** Not the oddest compound name in the city. There used to be a public market in Greenwich Village called the Jefferson Market. Then a courthouse was built adjacent to it and called, logically enough, the Jefferson Market Courthouse. Then the court was moved out and the derelict building saved in one of the city’s earliest successes in adaptive reuse and landmarking. The restored building was converted to a branch library which is technically the Jefferson Market Library but I will always think of it as the Jefferson Market Courthouse Library.