The Catskill Mountains are a large area in the southeastern portion of the U.S. state of New York. They are located approximately 100 miles north-northwest of New York City and forty miles southwest of Albany, starting just west of the Hudson River. The Catskills occupy much or all of five counties (Delaware, Greene, Schoharie, Sullivan, and Ulster). As a cultural and geographic region, the Catskills are generally defined as those areas close to or within the borders of the Catskill Park, a vast forest preserve protected from many forms of development under New York state law.
Geologically, the Catskills are a mature dissected plateau, a once-flat region subsequently uplifted and eroded into sharp relief by watercourses. The Catskills form the northeastern end of, and highest-elevation portion of, the Allegheny Plateau (also known as the Appalachian Plateau). Although the Catskills are sometimes compared with the Adirondack Mountains further north, the two mountain ranges are not geologically related, as the Adirondacks are a continuation of the Canadian Shield. Similarly, the Shawangunk Ridge, which forms the southeastern edge of the Catskills, is part of the geologically distinct Ridge-and-Valley province, and is a continuation of the same ridge known as Kittatinny Mountain in New Jersey and Blue Mountain in Pennsylvania.
Climatically, the Catskills lie within the Allegheny Highlands forests ecoregion. The Catskills are well known in American culture, both as the setting for many 19th-century Hudson River School paintings and as the favored destination for Jewish vacationers from New York City in the mid-20th century. The region's so-called "Borscht Belt" resorts gave countless young stand-up comedians an opportunity to hone their craft. In addition, the Catskills have long been a haven for artists, musicians, and writers, especially in and around the town of Woodstock.
At the eastern end of the range, the mountains begin quite dramatically with the Catskill Escarpment rising up suddenly from the Hudson Valley. The western boundary is far less certain, as the mountains gradually decline in height and grade into the rest of the Allegheny Plateau. Nor is there a consensus on where the Catskills end to the north or south, with it being certain only that by the time one reaches either I-88, the Delaware River or the Shawangunk Ridge that one is no longer in the Catskills.
In these peripheral regions, whether you are in the Catskills seems to be a matter of personal preference, as an old saying in the region seems to suggest — "When you have two rocks for every dirt, you are in the Catskills." Many visitors, including owners of weekend or vacation homes in the region, seem to consider almost anything sufficiently rural west of the Hudson yet within a short drive of New York City to be in the Catskills. The Poconos, to the immediate southwest in Pennsylvania, are technically a continuation of the Catskills under a different name. The Catskills contain more than thirty peaks above 3,500 feet and parts of six important rivers. The highest mountain, Slide Mountain in Ulster County, has an elevation of 4,180 feet (1,274 m).
Within the range is the Catskill Park, part of New York's Forest Preserve. Not all the land is publicly owned; about 60% remains in private hands, but new sections are added frequently. Most of the park and the preserve are within Ulster County; however Greene County accounts for a significant portion as well and there are areas in Sullivan and Delaware counties too.
From 1872, the Catskills were served by the Catskill Mountain Branch of the Ulster and Delaware Railroad which was absorbed into the New York Central railroad in 1932. Passenger rail service continued until 1954. Part of the line still exists but now serves only freight. The Catskills are accessible by automobile from the east along Interstate 87, part of the New York State Thruway, which runs north-south through the Hudson Valley.
To the south and southwest, the Catskills are accessible by a variety of highways, including New York State Route 55, U.S. Route 44, U.S. Route 209, and New York State Route 17 (also known as "Future I-86"). Access to the western Catskills is provided by New York State Route 30; and the vaguely defined far-western edge of the region is variously considered to be New York State Route 10 or Interstate 88, though this boundary remains a matter of local preference. New York State Routes 28 and 23A cut east-west through the heart of the Catskills, serving many of the most popular outdoor tourist destinations. New York State Route 23 runs east-west across the Catskills' far-northern section.
The closest major airports to the Catskill region are Albany International Airport to the north and Stewart International Airport in Newburgh to the south. Smaller airports in the region include the following: