Here's a short story:

The Ohio River, which streams westward from Pittsburgh, Pennsylvania, to Cairo, Illinois, is the largest tributary, by volume, of the Mississippi River in the United States. At the confluence, the Ohio is considerably bigger than the Mississippi (Ohio at Cairo: 281,500 cu ft/s (7,960 m/s); Mississippi at Thebes: 208,200 cu ft/s (5,897 m/s)) and, thus, is hydrologically the main stream of the whole river system. 

The river flows through or along the border of six states, and its drainage basin includes parts of 15 states. Through its largest tributary, the Tennessee River, the basin includes many of the states of the southeastern U.S. It is the source of drinking water for three million people. 

It is named in Iroquoian or ,  "Good River" or and "Spelewathiipi". The river had great significance in the history of the Native Americans, as numerous civilizations formed along its valley. For thousands of years, Native Americans used the river as a major transportation and trading route. Its waters connected communities. In the five centuries before European conquest, the Mississippian culture built numerous regional chiefdoms and major earthwork mounds in the Ohio Valley, such as Angel Mounds near Evansville, Indiana, as well as in the Mississippi Valley and the Southeast. The Osage, Omaha, Ponca and Kaw lived in the Ohio Valley, but under pressure from the Iroquois to the northeast, migrated west of the Mississippi River to Missouri, Arkansas and Oklahoma in the 17th century. (End of story)

Provide your best guess for the following question. Give ONLY the guess, no other words or explanation.

For example:

Guess: <most likely guess, as short as possible; not a complete sentence, just the guess!>

Here are a few examples of questions and answers:

Question: How many state doe the Ohio River go through or by?
Guess: six

Question: How many are included in it's drainage basin?
Guess: 15

Question: How many people use it for drinking water?
Guess: three million

Question: What is one of its tributaries?
Guess: Tennessee River

Question: Where does that rank in size among all its tributaries?
Guess: The largest

Question: What river is the Ohio River a tributary of?
Guess: Mississippi

Question: How is that measured?
Guess: cu ft/s

Question: Which way does it flow?
Guess: westward

Question: Beginning where?
Guess: Pittsburgh

Now answer the following question in the same format.

Question: Where is that?

Pennsylvania