Founded in 1809, Sullivan County is one of 62 counties in the state of New York. Historically, Sullivan County was formed from Ulster County. The city of Monticello is the county seat. With FIPS code of 105, Sullivan County has a population of 79,806 and area of 997 square miles (2,582 km2).
List of all cities in Sullivan County, NY alphabetically
| City/Town | Postal Code | Area Code |
| Barryville, NY | 12719 | 845 |
| Bethel, NY | 12720 | 845 |
| Bloomingburg, NY | 12721 | 845 |
| Burlingham, NY | 12722 | 845 |
| Callicoon, NY | 12723 | 845 |
| Callicoon Center, NY | 12724 | 845 |
| Claryville, NY | 12725 | 845 |
| Cochecton, NY | 12726 | 845 |
| Cochecton Center, NY | 12727 | 845 |
| Eldred, NY | 12732 | 845 |
| Fallsburg, NY | 12733 | 845 |
| Ferndale, NY | 12734 | 845 |
| Forestburgh, NY | 12777 | 845 |
| Fremont, NY | 12736 | 845 |
| Fremont Center, NY | 12736 | 845 |
| Glen Spey, NY | 12737 | 845 |
| Glen Wild, NY | 12738 | 845 |
| Grahamsville, NY | 12740 | 845 |
| Hankins, NY | 12741 | 845 |
| Harris, NY | 12742 | 845 |
| Highland Lake, NY | 12743 | 845 |
| Hortonville, NY | 12745 | 845 |
| Hurleyville, NY | 12747 | 845 |
| Jeffersonville, NY | 12748 | 845 |
| Kauneonga Lake, NY | 12749 | 845 |
| Kenoza Lake, NY | 12750 | 845 |
| Kiamesha Lake, NY | 12751 | 845 |
| Lake Huntington, NY | 12752 | 845 |
| Lew Beach, NY | 12758 | 845 |
| Liberty, NY | 12754 | 845 |
| Livingston Manor, NY | 12758 | 845 |
| Loch Sheldrake, NY | 12759 | 845 |
| Long Eddy, NY | 12760 | 845 |
| Mongaup Valley, NY | 12762 | 845 |
| Monticello, NY | 12701 | 845 |
| 12777 | 845 | |
| Mountain Dale, NY | 12763 | 845 |
| Narrowsburg, NY | 12764 | 845 |
| Neversink, NY | 12765 | 845 |
| North Branch, NY | 12766 | 845 |
| Obernburg, NY | 12767 | 845 |
| Parksville, NY | 12768 | 845 |
| Phillipsport, NY | 12769 | 845 |
| Pond Eddy, NY | 12770 | 845 |
| Port Jervis, NY | 12785 | 845 |
| Rock Hill, NY | 12775 | 845 |
| Roscoe, NY | 12776 | 607 |
| Smallwood, NY | 12778 | 845 |
| South Fallsburg, NY | 12779 | 845 |
| Summitville, NY | 12781 | 845 |
| Sundown, NY | 12740 | 845 |
| Swan Lake, NY | 12783 | 845 |
| Thompsonville, NY | 12784 | 845 |
| Westbrookville, NY | 12785 | 845 |
| White Lake, NY | 12786 | 845 |
| White Sulphur Springs, NY | 12787 | 845 |
| Woodbourne, NY | 12788 | 845 |
| Woodridge, NY | 12789 | 845 |
| Wurtsboro, NY | 12790 | 845 |
| Youngsville, NY | 12791 | 845 |
| Yulan, NY | 12792 | 845 |