Olean is a city in Cattaraugus County, New York, United States. Olean is the largest city in Cattaraugus County, and serves as the financial, business, transportation and entertainment center of the county. It is one of the principal cities of the Southern Tier region of New York. The city is surrounded by the Town of Olean and is located in the southeastern part of the county. The population was 15,347 at the 2000 census. The 2006 population estimate by the U.S. Census Bureau is 14,584.