Averill Park is a census-designated place within the town of Sand Lake in Rensselaer County, New York, United States.

[3] Originally known only as part of greater Sand Lake, the community along with neighboring towns grew with the nineteenth-century development of wool and cotton textile manufacturing by local watermills and knitting factories along the Wynants Kill tributary of the Hudson River.

[6] The hamlet was named Averill in 1880 after a local leading family, then in 1882 renamed Averill Park in promotion of local summer-resort development[7] and of the Troy & New England Railway, a never-completed trolley and freight line intended to connect the city of Troy, New York with the mills and summer resorts of Averill Park and its “upstate Coney Island” recreational Crystal Lake Beach, and with the mills of the neighboring town of West Sand Lake.

[8] The local mills declined after the increasing efficiency of steam and electrical power improved competition from regional factories, and were then destroyed by a 1891 river flood.

[9] Other late-nineteenth- and early-twentieth-century firms included Jake Warger’s Dry Goods Store; Gilbert Beebe’s blacksmith shop; Stout’s Hardware; and Park Pharmacy, where Jerry Lewis worked as a soda jerk in 1942 when his father was a superintendent at Faith Mills.

[12] During World War II, manufacture of wool blankets and long woolen underwear for the military earned Faith Mills four rare “excellence in production” Army-Navy "E" Awards.

[13][14] From 1955 to 1962, Faith Mills, by then one of only three remaining U.S. manufacturers of woolen long underwear “considered obsolete by most persons” as the market shifted to cotton undergarments, was sold to holding companies and downsized to one factory in Averill Park employing as few as 54 workers, finally closing in 1962.

[21] Arts Letters & Numbers, on Burden Lake Road, is a nonprofit arts center offering workshops, performances, and residencies,[22] housed in a complex including the former Sand Lake Cotton Factory, which operated as Arnolds, Hunt & Co. until 1875 and was later run by Faith Mills; and also the residence built by mill owner George Arnold.