5" x 7". 100% recycled matte cardstock. To order more than 19, you must choose "19+" from the quantity drop-down, and then edit the number for the quantity you desire. The Catskill Mountains, also known as the Catskills, are a large area in the southeastern portion of the U.S. state of New York. The Catskills form the northeastern end of, and highest-elevation portion of, the Appalachian Plateau. 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 urban vacationers from New York City in the mid-20th century. Original artwork by Catherine LaPointe Vollmer.