A small swampy area was ﬁrst called a vly by early Dutch colonists in what is now New York, perhaps the earliest occasion being on Long Island, but also in the Hudson Valley. This Dutch word, usually indicating the marshy headwaters of a brook or stream, where the water table ﬁrst surfaces, is little used anymore, though many New York place-names retain it, including Vly Mountain in Greene County, Vly Lake in Hamilton County, and Vly Brook in Herkimer County. It can connote low ground, sometimes under water, a marsh or creek. One plausible etymology, proposed by lexicographers with some uncertainty, suggests that the old Dutch name for “market,” vly—which also meant “valley,” and which was pronounced “ﬂea”—may have occasioned the name of New York’s rowdy Fly Market, which was a ﬁxture of Lower Manhattan from before the Revolution until about 1816. But this may be fanciful.