[6] As Europeans explored the coastal regions reachable from ships at the dawn of the 17th Century, the whole valley of the Susquehanna from South-central New York state to the upper Chesapeake Bay was owned by the fierce Iroquois-like Susquehannock people, like the Erie people, an Iroquoian speaking tribe with a similar related culture.

1600 AD the protestant Dutch traders first entered the Delaware Valley and began regularly trading firearms for furs, especially highly valued beaver pelts with the inland Susquehannock people in the vicinity of greater Philadelphia.

Although the Susquehannocks lived well inland their hunting range owned the rich Beaver territory of the entire Susquehanna River drainage basin, since the Susquehannock's range also included hunting the Schuylkill and Lehigh Rivers and their tributaries (which they historically disputed by occasional mutual raiding with the Algonquian Delaware people dwelling along the Atlantic coastal strip extending west from Delaware and southern New Jersey into the Poconos), the Susquehanna had a wealth of coveted Beaver pelts, and so became formidably well armed.

About the time New Sweden (1638) was founded, the Iroquois Confederacy began a series of escalating wars setting Indian versus Indian called the Beaver Wars—that ultimately would open up the frontier to white settlers—deadly long running territorial wars between Amerindian peoples for fur hunting and trapping territories.

Forearmed by their traders knowledge, the Swedes settled both sides of the Delaware, and almost immediately became allies with the Susquehannock, who already well armed, would soon after have a confederacy well armed enough to win a war declared by the colonial Province of Maryland, subjugate several Delaware tribes and would inflict several stinging defeats on Iroquois forces.

[7] They were a fierce and powerful people holding off territorial infringements from the tribes on all sides of their range from the Potomac to the Mohawk valley, and the Poconos to the Alleghenies.

[7] Danville, located in the southern center of the valley would have been at least a summer hunting camp for these people, who were to become horribly affected by epidemic plagues of disease over multiple years circa 1668-72.

[7] This sudden weakness in population ironically occurred shortly after the Susquehannocks gave a serious drubbing about 1665-66 over 2-3 years[7] to two of the Five Nations of the Iroquois in the local Beaver Wars.

After the drastic weakening, they were attacked on all sides by subjected tribes, colonists, and the Iroquois, suffering further large losses.

[7] By 1678, the Iroquois would agree in a treaty to absorb most of the remaining Iroquoian Susquehannocks whose civilization had collapsed,[7] though several hundred remnants migrated to live south and west of the Wyoming Valley, and would be called the Conestoga by the new English settlers in the colony of Pennsylvania,[7] whilst the Susquehannock confederation would go extinct as an Iroquoian people and its surviving people would be absorbed into other tribes.

Following his service in the New York and New Jersey Campaign, William re-settled his family from Chester County to Northumberland.

Subsequently, it became served by several railroads also running along the banks of the North Branch of the Susquehanna River.

Railroads helped local businesses expand their sales as they supplied major cities outside of Danville.

Many of the rails of the nation's expanding railroad system were made in Danville, an important contribution to a network which grew explosively for decades.

In 1869 the Danville State Hospital was built as a state institution for the treatment and care of the mentally ill. Abigail Geisinger, widow of iron magnate George Geisinger, used his fortune to build a hospital and clinic intended to be a regional medical center modeled after the Mayo Clinic.

In the early 1960s, local company Susquehanna Danville Airport produced airboats for evaluation by the U.S. Army.

According to the United States Census Bureau, the borough has a total area of 1.6 square miles (4.1 km2), all land.

They hope to attract state funding to study recreational opportunities along the Susquehanna River.

The Montour Area Recreation Commission (MARC) led a local volunteer effort to clear the abandoned towpath of the North Branch Canal along the Susquehanna River.

A mile of the towpath was cleared, permitting biking, walking and running near the Danville Soccer Park.

The long-term vision is to create a regional trail that connects Northumberland to Catawissa and on to Bloomsburg, Pennsylvania.

Running through the outskirts of Danville, the J. Manley Robbins trail is alleged to be the oldest documented rail-trail in the United States.