These days Harrisburg NC is a Top 50 Place to Live.

http://time.com/money/collection-post/3984481/harrisburg-north-carolina-best-places-to-live-2015/

Not a lot of detailed history of Harrisburg, NC or Pharr Mill is available online.

https://www.harrisburgnc.org/about-harrisburg/history

https://en.wikipedia.org/wiki/Harrisburg,_North_Carolina

But, it is known that long before the town arranged to get electricity grid service in 1928, there was a state law granting 50 acres of land and exemption from taxes and service in the state militia to gristmill and sawmill operators. It is believed that the first Pharr Mill was built about 1850 on this site by Hugh Smith Pharr. The original mill washed away in a flood in about 1910, and was replaced in the current location by Paul Stallings in about 1912.The Stallings family donated the structure and 8 acres of land to the town in 1998. It has deteriorated significantly since then.

http://tedmccachren.com/historic/electricity.html

https://www.ncpedia.org/gristmills

http://tedmccachren.com/restoration/pm-history.html

http://tedmccachren.com/restoration/pharrmill.html

Gristmills in general have a much longer history.

https://en.wikipedia.org/wiki/Gristmill

In contrast, other nearby companies such as Mineral Research and Development Corp. aka Chemical Specialties LLC, just north (less than 0.2 miles) of the old gristmill, have more recent and detailed history, in more modern business, with many details available from EPA and Scorecard.

https://oaspub.epa.gov/enviro/multisys2_v2.get_list?facility_uin=110057679739

http://scorecard.goodguide.com/env-releases/facility.tcl?tri_id=28075MNRLRHWY49

On this old gristmill site, you can see the old mill building, as well as what is left of the dam and water works. Much of the equipment has been removed, but there is still some remaining, including stone grinding wheels, which are visible through the fence. Please do not trespass inside the fence, for your own safety.

I thought I'd make this a letterbox hide for a few reasons. First, there were no OCUS letterbox hides within over 300 miles from Harrisburg, if my search fu isn't fubar. Second, letterboxing has a history starting nearly the same time as the first mill was built here, in the 1850s. Lastly, I appreciate the artistic aspect of letterbox stamps, even if I've never really had one. The fact that letterboxes could be found without GPS is an interesting twist too, these days. This might qualify me for one more OCUS challenge find too!

https://en.wikipedia.org/wiki/Letterboxing_%28hobby%29

https://www.atlasquest.com/about/history/index.php

To find this cache... parking is available at the pullout at the corner of Pharr Mill Road and Shamrock Road. You should see the old mill building as you approach. The posted coordinates are near the "far corner" of the fence around the building. DO NOT go inside the fence for this cache.

Near the back corner of the fence you should find an item you will need to scan with an NFC reader to get the final coordinates. If you don't have a device with NFC scanner, you should buy a different phone, or bring a friend who has one. :)  I thought this was a fun, modern contrast to the old letterbox methods. Alternatively, see the hint for more old fashioned directions. Please let me know in your log which method you used.

You will need to cross the small creek (but not Rocky River!) to get to the final location. It's a bit steep in most places, and may be slippery when wet. Another route we used is to go along the land along/above Rocky River, and climb up over the stone work. This may also be slippery when wet, so watch your step.

You're looking for a large ammo can. If you have a letterbox stamp, use it to stamp the log. Otherwise, feel free to sketch something, or simply sign. The provided stamp isn't fancy, but it's there for your stamp log if you have one.

Be sure to make note of the e-logging password on the first page of the log.

I hope you enjoy the history and short walk in the woods.