PENNSYLVANIA (WHTM) — Pennsylvania is full of unique geographical features such as mountains, lakes, hills, and fields. Rivers are also found in many parts of the state. Some are as short as 123 miles and as long as 981 miles.

Here are some of the longest rivers that flow through the Keystone State.

Allegheny River- 325 Miles

Rising from a region in Potter County, this river flows through New York and Pennsylvania and has been made possible upstream of Pittsburgh by locks and dams that were built in the early 20th century. According to rivers.gov, this river provides the most populous freshwater mussel habitats in the world.

This river joins the Monongahela River in Pittsburgh to form the Ohio River. This river, according to Britannica is also known for its scenic banks and vacation sites.

Deleware River- 330 miles

The river begins as two branches in the Catskill Mountains of New York, with the Westen Branch beginning near Mount Jefferson, and the Eastern Branch starting in Roxbury. The two branches meet in Hancock, New York, and flow as one river all the way to Deleware Bay.

This river runs through New York, New Jersey, Pennsylvania, Maryland, and Delaware, and provides drinking water to over 13 million people, according to the Water Shed Alliance.

Susquehanna River- 444 Miles

This river is the longest river on the East Coast of the United States and the 16th longest in the country. The river begins in upstate New York and flows into the Chesapeake Bay in Maryland. It is also the longest non-commercially navigable river in the country.

There are two branches of the river, with the west branch beginning near Sunbury. Visitcenteralpa.org states that a daily rush of 22 billion gallons flows into the Chesapeake Bay each year, which makes it the largest contributor of fresh water to the bay.

Ohio River- 981 miles

This river flows through many states, but it starts at the confluence of the Allegheny and the Monongahela Rivers in Pennsylvania. This river ends all the way to Illinois, where it empties into the Mississippi River. The National Park Service says that this river was the southern border of what was known as the Northwest Territory in the Late 18th century

In total, the river is the source of drinking water for around 5 million people in the country. The average depth of this river is 24 feet, but its deepest part is 130 feet near Louisville, Kentucky.