There are larger trail systems and more spectacular views, but the Northeast US has the most dense concentration of cross-country ski areas and trails of any region in the US. Northeasterners get really nice views as well from some places (Minnewaska, Great Glen), and a sense of speed from skiing in the trees.
The combined Google map below features some of the parks and ski areas available for cross-country skiing in the downstate NY area (conditions permitting of course!), and some (but by no means all) of the XC ski centers and resorts within a day’s drive of NYC. See the List of Touring Centers or Nearby Parks and Trails for additional info. Many parks and golf courses permit skiers in winter; check specifically or with some cross-country skier groups for suggestions.
Legend for the markers below. The tree icon means trails are not maintained or groomed. XC ski centers are given icons and color-coding by type and services. Parks, non-profits, and clubs typically have basic amenities (a simple warming hut and maybe toilets); ‘rustic’ touring centers will often have a cottage or barn as a warming hut, and may have rentals and food. Regular touring centers are a step up in having the ‘tourist-friendly’ essentials of rentals and food, as well as a lodge. Specialty resorts can range from country inns to athlete/fitness oriented. Full-service resorts are just that. Call ahead means they have/had trails but don’t post conditions much, or it’s advisable to check before going.