At the time of European colonization(circa AD1500), Bison ranged east of the Mississippi River up into Western New York(hence, the city of Buffalo), south through the western sections of the Mid-Atlantic States down through western Florida................."Pennsylvania contains numerous examples of locations named after buffalo".................."In frontier culture, people often named their lands after a rare or unique sighting of wildlife, such as White Deer, Bald Eagle, or Native American names like Swatara (“where we feed on eels”) and Moosic (“place of moose”)"................."The sheer numbers of buffalo place names makes a very strong case that some of the earliest white settlers in the Susquehanna region almost certainly encountered buffalo or Indians who related buffalo sightings".................."The year, 1801, is in the same general time period when the animals were killed off in neighboring states"................."By 1730 buffalo were gone from the tidewater region of Virginia; in 1808 the last Ohio buffalo was killed, and by 1825 the last was killed in western Virginia"................."Southwestern Pennsylvania probably had a higher number of buffalo, still far from the herds of thousands described by Shoemaker, but that would be the region expected to harbor the last hold out of the species".................."It is possible however that a small herd of animals was pushed to the northeast and temporarily into the Susquehanna Watershed"..................."As various militaries and explorers increased hunting pressure on the area around Fort Pitt, modern day Pittsburgh, the mountains and valleys of central Pennsylvania may have offered a refuge for a short time until that region too began filling with Europeans and their rifles".................."By 1600 bison had recolonized the south as far east as St. Simon’s Island, Georgia where bison bones were found in an Indian mound located in Chatham County"................"Bison bones dating to 1700 were found in Clay County, Florida at the former site of a Spanish settlement known as Fort Pupo"................"General Oglethorpe, who founded the state of Georgia, went hunting for bison in 1733"................"Edward Kingo saw 100 bison on one acre of ground near Abbeville, Georgia about this same time period"............."Buffalo licks consisting of minerals or clays attracted huge herds of bison"..............."The Great Buffalo Lick in east central Georgia was covered in white clay-colored dung, and great pits were licked from the soil by large herds of bison".............."Bison congregated around Big Bone Lick and Blue Licks in Kentucky for the mineral salts"................."James Couper shot the last known bison in Georgia circa 1800, near the Turtle River, a coastal waterway"............."This was also the last bison known from the Atlantic Coast"

The range of the American Bison is mapped above, with the plains bison in darker brown and the larger woods bison in lighter brown. The lightest color denotes the range extent of Ice Age bison.

http://www.vanwagnermusic.com/vanwagnermusic/buffalo.htm

History of Buffalo in Pennsylvania by Watershed.

The strongest evidence of Bison relates to the Ohio River watershed.  There are several 18th century accounts of buffalo sightings in the southwest part of the commonwealth.  The Moravian missionary John Heckewelder, who crossed the Allegany Mountains over sixty times and logged 30,000 miles on the frontier, recorded them in this region in the 1770’s.  In 1773 he documented meeting an Indian near Marietta, Ohio, “on his way home from a hunting trip.  He had shot a buffalo ox, of which there are many hearouts.”1 This is less than 50 miles from the Pennsylvania border. 

Another reference to buffalo in this region comes from Lewis Ourry’s letter from fort Bedford to Henry Bouquet on Feb 21, 1760: “Yesterday I forwarded downwards the General’s Baggage, consisting of 5 wagon, each drawn by 6 horses one slope wagon by 4, and a chair by 1 and 5 spare in all 40, and a young Buffalo.”  The General he referred to was John Stanwix, who had been stationed at Pittsburgh since August 1759.  Since there was no British post beyond Fort Pitt at this time, this buffalo almost certainly came from the immediate region.

Some researchers have suggested that a severe drought on the plains in the 1600’s encouraged buffalo herds to migrate up the Mississippi River to the Ohio River and its headwaters.6  In addition, thousands of acres of land originally cultivated by Native Americans were temporarily abandoned as white encroachment and European diseases forced Indians from their lands.

Some have argued that buffalo could not have existed in Pennsylvania due to a lack of grazing habitat.  Indeed, the heavily forested ecosystem that was Pennsylvania in the 17th an 18th centuries did not provide much in the way of food for bison.  Instead, Pennsylvania would have classified as fringe habitat - providing just enough low land and floodplain grazing to support the occasional buffalo.

  Also, the temporary availability of what had been Native American cropland could account for a small natural food supply for grazing ruminants just about the time that the specie was moving east in its range.  Whether due to human demographic changes or by natural processes, the plains buffalo was beginning to broaden its range towards south and western Pennsylvania.  This leads to the question of exactly which watershed regions of Pennsylvania may have supported some buffalo.

As previously established, buffalo were present in the Ohio River watershed.  An additional account of buffalo in this region comes from soldiers from Fort Cumberland in 1763.  While serving under Captain Luke Collins the men followed a group of Indians up to the Cheat River, A tributary of the Monongahela River, and attacked them while “they were barbequing a Buffaloe, not thinking of danger

In the south central portion of the state is the region of the Potomac drainage, here is a possibility that buffalo were occasionally found in this region.  In 1612 European explorer Samuel Argall, often a bit off bearing, reported seeing “a great store of cattle as big as kine…”  within 15 miles of present day Washington, D.C.11  Maryland, West Virginia, and western Virginia all have solid documented sightings of buffalo.

Pennsylvania contains numerous examples of locations named after buffalo.  In frontier culture, people often named their lands after a rare or unique sighting of wildlife, such as White Deer, Bald Eagle, or Native American names like Swatara (“where we feed on eels”) and Moosic (“place of moose”).  The sheer numbers of buffalo place names makes a very strong case that some of the earliest white settlers in the Susquehanna region almost certainly encountered buffalo or Indians who related buffalo sightings.

Dots indicate buffalo place names in Pennsylvania.  By Karl Shellenberger 2007

The year, 1801, is in the same general time period when the ani
mals were killed off in neighboring states.  By 1730 buffalo were gone from the tidewater region of Virginia; in 1808 the last Ohio buffalo was killed,T and by 1825 the last was killed in western Virginia.15  The location of the Pennsylvania legend, however, is a bit unexpected.  Southwestern Pennsylvania probably had a higher number of buffalo, still far from the herds of thousands described by Shoemaker, but that would be the region expected to harbor the last hold out of the specie.  It is possible however that a small herd of animals was pushed to the northeast and temporarily into the Susquehanna Watershed. As various militaries and explorers increased hunting pressure on the area around Fort Pitt, modern day Pittsburgh, the mountains and valleys of central Pennsylvania may have offered a refuge for a short time until that region too began filling with Europeans and their rifles.
  
It is worth noting that small pockets of grassland habitat did indeed occur along the Susquehanna.  In 1743 the botanist William Bartram explored the region and noted “Our journey now lay through very rich bottoms to a creek, six miles from Shamokin [Chillisquaque Creek], a great extent of fruitful low ground still continuing.  Here we found a fine meadow of grass on our right, and rich dry ground on the left…” 16 Shamokin was located at modern day Sunbury.  Bartram was describing the Chillisquaque creek in the area of modern Montandon.  He does not, however, mention seeing any buffalo in his travels through the watershed.  That being said, he does not mention other animals such as elk, moose, or deer, all of which did occur there.
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https://www.wildwill.net/blog/2015/07/12/the-history-of-bison-in-southeastern-north-america-2/

The History of Bison in Southeastern North America

Mark Gelbart; July 12, 2015

 There is no certain fossil evidence of  of plains bison in southeastern North America until 1600 AD. However, bison were able to recolonize southeastern North America during the late 1500’s because infectious diseases brought by Europeans decimated Indian populations. Much of Indian farmland reverted to wilderness

Bison populations expanded east where they found favorable habitat on abandoned Indian fields, and natural grassy environments. The surviving Indians continued setting fire to the woods every year, a management practice that improved habitat for wildlife by creating open woodlands with grassy understories. Bison could feed upon grass year round along with bountiful crops of acorns produced by widely spaced oaks in the fall. Mature oak and pine trees are fire resistant, but fire destroys the saplings and brush — a process of “thermal pruning.” Extensive canebrakes that stretched for miles occurred on most river and creek bottomlands in the piedmont region. Bamboo cane was another source of fodder for expanding bison populations.

Grasslands in the south were not dependent upon man-made fires. Studies show lightning strikes in the south are frequent enough to spark wildfires that can maintain grassy environments. Lightning-induced fires created the longleaf pine savannahs that formerly predominated on the coastal plain for millions of years. This was ideal habitat for bison and other grazers as were serpentine barrens–areas of soil with high concentrations of heavy metals that allow grass to outcompete trees. Other types of natural grasslands in the south that supported bison included alkaline cedar glades, Kentucky bluegrass savanna/woodland, Louisiana coastal prairies, and The Black Belt Prairies in Alabama and Mississippi.

By 1600 bison had recolonized the south as far east as St. Simon’s Island, Georgia where bison bones were found in an Indian mound located in Chatham County. Bison bones dating to 1700 were found in Clay County, Florida at the former site of a Spanish settlement known as Fort Pupo. General Oglethorpe, who founded the state of Georgia, went hunting for bison in 1733. Edward Kingo saw 100 bison on one acre of ground near Abbeville, Georgia about this same time period. Buffalo licks consisting of minerals or clays attracted huge herds of bison. The Great Buffalo Lick in east central Georgia was covered in white clay-colored dung, and great pits were licked from the soil by large herds of bison. Bison congregated around Big Bone Lick and Blue Licks in Kentucky for the mineral salts.

European settlers over-hunted bison to extirpation in the south during the 18th century. William Bartram, a famous naturalist, never saw a live bison when he traveled through the region in 1775 and 1776, though he did see the skulls of bison mixed with bones of deer, elk, and humans on a serpentine barren hill top.4

James Couper shot the last known bison in Georgia circa 1800, near the Turtle River, a coastal waterway. This was also the last bison known from the Atlantic Coast. The last bison in Pennsylvania was shot in 1801. The last Louisiana bison was killed in 1803. Bison were extirpated from Kentucky in 1820, from Tennessee in 1823, and from West Virginia in 1825. Bison trails (or traces) remained visible for decades after their disappearance from the region. The bison herds caused these trails to have a sunken denuded structure, and settlers used these hard-packed eroded trails as roads. Many became state highways.

The extirpation of bison in the south caused a profound loss of ecological diversity. Bison maintained open areas by trampling, grazing, and eating acorns, thus reducing tree germination. Ground squirrels, prairie chickens, bobwhite quail, upland sandpipers, meadowlarks, and burrowing owls are just a few of the animals that benefitted from the presence of bison. Bison increased the fertility of the soil and enhanced seed dispersal by consuming plants and defecating all over the landscape. Their dusty wallows served as refuges for toads and countless species of insects. Once common species of plants became rare: short’s goldenrod (Solidago shortii) and running buffalo clover (Trifolium stoloniferum) depended upon heavy grazing and trampling to reduce competition. Now both of these species are nearly extinct.