Counties:
Towns and cities:
Moore, Carl (1996-02-12). "history.of.area.splits". TELECOM Digest. Archived from the original on 10 July 2012. Retrieved 2007-01-06. Also published in newsgroup comp.dcom.telecom https://archive.today/20120710002143/http://massis.lcs.mit.edu/archives/areacodes/history.area.splits.2-96 ↩
"Transition to 10-digit dialing (for 988 as 3-digit access to National Suicide Prevention Hotline)" (PDF). North American Numbering Plan Administrator. January 8, 2021. Retrieved March 9, 2021. https://nationalnanpa.com/pdf/PL_556.pdf ↩