I originally ran across this in the Winter 2015-2016 print edition of American Archaeology, but the article, a book review, doesn’t appear to be online. A little search online turned up The Ancient Earthworks Project to confirm:
The Adena and Hopewell aligned many of their earthworks to celestial events such as solstices. They also built many earthworks in geometric shapes and used standard units of measurement (Hively and Horn 1982; Romain 2000). One of these units of measurement is equal to 1,054 feet. For convenience, we can call this the Hopewell Measurement Unit, or HMU. Thus 1 HMU = 1,054 feet. This unit of length is based on the diameter of the Newark Observatory Circle (Thomas 1894:16). This unit of length or its sub-multiples (e.g., 527 ft., 263.5 ft., 131.7 ft.) are found in the dimensions of every Hopewell earthwork assessed thus far, as well as most Adena earthworks. – William F. Romain, Ph.D.
Links added by myself.
So there you have it. The Hopewell Measurement Unit is 1054 feet.
