I found this land record for "Cooper's Purchase" in 1998 in the Washington county, PA. courthouse. This 300 acres of land that Edward Coyan & family resided on in Hanover township from 1798 until ca. 1812 (and where son William is confirmed to have been born in the Hanover township village of Florence in 1805) was owned by Thomas Cooper, as confirmed in the 1798 Federal Direct Tax List for PA.
This 1798 record shows Edward as the "tenant". Now all I have to do is figure out exactly where this land is located - not an easy task. Noting the "next door" neighbors to our ancestor Edward (as it seems to be documented in the 1810 census) and exactly a location for THEIR land may be a clue as well. I drove through Florence, PA. (basically just a "crossroads") on one of my many trips to PA. in 1998 and it is today just as it was (probably) 200 years ago - rolling rolls, very sparsely populated, and consisting of rural farms ( I wonder if the "rolling hills" reminded Edward of "home" in Maryland - or even Ireland!)
One of my ultimate goals is to find the exact location and set foot on the land that all Coyan descendant's (and my 5th great-grandparents) lived and raised their children from ca. 1798 until about 1812.