Ivy Mills is mentioned in the book "Old Roads out of Philadelphia" by John Thomson Faris published in 1917 and found at this Google Books link:
pp. 7-8 of this book list several sources I haven't looked at yet (and that look really great to delve into). Histories, journals, letters, guide books.
A place to gather and share information about the Thomas Willcox and Elizabeth Cole Willcox Family of Ivy Mills, PA. For more information see the Home page link above or contact Deniane Kartchner at Denianek@gmail.com. My husband is a descendant of Thomas and Elizabeth's son James who married Prudence Doyle. Their son John's daughter Prudence married John Christopher Kartchner.
Note: This is a work in progress! I am trying to verify everything before I post, but feel free to send me corrections and/or suggestions. It’s also not a complete history of Ivy Mills or a website for current operations, although I will gladly try to answer any questions and/or lead you to the right information.