Olean is the largest city in Cattaraugus County and serves as its financial, business, transportation and entertainment center.

The first European in the area was possibly Joseph de La Roche Daillon, a missionary and explorer from Canada.

La Roche reported on the presence of oil near Cuba, the first petroleum sighting in North America.

During the American Revolutionary War, the 1779 Sullivan Expedition established the first road to what would become Olean, blazing a trail to what is now Kittanning, Pennsylvania along the path of what is now New York State Route 16.

Originally the entire territory of the county of Cattaraugus was called the Town of Olean, formed March 11, 1808.

Hinsdale formed in 1820, and Portville in 1837, leaving the current boundary of Olean that lies upon the south line of the county, near the southeast corner.

The area remained sparsely populated until 1804, when Major Adam Hoops acquired the land and gave it its modern name.

Hoops was a surveyor and Revolutionary War veteran, and was politically connected with Robert Morris, the financier of the Revolution.

Hoops believed that a great city could be created at the confluence of the Allegheny and one of its tributaries and went looking for the right spot.

Dear Sir,―It was proposed to me at New York to drop the Indian name of Ischue or Ischua (it is also spelt other ways).

To begin, you will greatly oblige me by addressing the first letter you may have occasion to write to me, after I receive the survey, to the Mouth of Olean.

In 1854 Olean was formally incorporated by the New York State Legislature, and the trustees elected at the first subsequent town meeting were Lambert Thithney, C.B.B.

[2] Adam Hoops's dream of creating a major transportation hub on the Allegheny River, on the scale of a Buffalo or a Pittsburgh, was never realized and he himself died in poverty.

Olean grew quickly as a transportation hub for migrants taking the Allegheny River into Ohio.

During the late-19th century, Olean had a few mills, a bicycle company, a manufacturer of mechanical pumps and a glass works, among other factories.

Oil produced on both sides of the state line (e.g. in Bradford, Pennsylvania) would be transported to Olean for rail travel.

For a short time, Olean was the world's largest oil depot, complete with a "tank city" on the edge of town.

He did not aggressively pursue arrests, however, unless he had evidence that the violator was responsible for a crime committed in his jurisdiction.

Olean, located on a back-road route between Chicago and New York City, was often frequented by famous mobsters of the era.

Al Capone of Chicago, probably the most famous gang leader of the time, visited Olean in pursuance of his illegal endeavors.

Olean was nicknamed "Little Chicago" in the press, due to its connection with mobsters and bootleggers, and Capone was a frequent visitor.

[5] In September 1968, Olean was the first city in the United States to install video cameras along its main business street in an effort to fight crime.

[8] The city is located where Olean Creek flows into the Allegheny River and by the Southern Tier Expressway (Interstate 86 and New York State Route 17).

[16][17][18] The Church of St Mary of the Angels on Henley Street was built in 1915 and was designated by Pope Francis as a basilica in 2017.

Until January 6, 1970, the Erie Lackawanna Railroad operated through Olean with the Chicago - Hoboken, New Jersey " Lake Cities": the last passenger train to traverse the entire Southern Tier.

[23] The nearest general commercial airports with scheduled flights for the public are in Erie, Buffalo and the Elmira area.