During the early 1780s, Cooper became a storekeeper in
Burlington, New Jersey, located along the
Delaware River. By the end of the decade, he was a successful land speculator and wealthy frontier developer in what is now
Otsego County, New York. Soon after the conclusion of the
Revolutionary War, he acquired a tract of land several thousand acres in extent within the borders of New York state and lying along the head waters of the
Susquehanna River at
Otsego Lake. He founded the Village of Otsego at the foot of the lake in 1786, creating a traditional plan for the village inspired by that of Burlington. He moved his family there, arriving on November 10, 1790. The judge and other investors also founded
De Kalb, New York, near the east end of
Lake Ontario and the
St. Lawrence River, in 1803, platting approximately 64,000 acres and selling the parcels on. His brother James took care of the holdings, which were tied up in litigation for years, both before and after the death of Judge Cooper in 1809. The Cooper family holdings were all gone by 1817. In 1852, a village was named Cooper's Falls north of De Kalb. James stayed in the area, and his son William grew up in De Kalb and was a carpenter. The existing De Kalb Historical Society building was built by the judge's nephew, William, and some of his descendants may still live in the area. After 1791, when Otsego County was split off from
Montgomery County, Cooper was appointed as a county judge. He was later elected to two terms in Congress, representing the
Federalist Party in the
4th (March 4, 1795 – March 3, 1797) and the
6th United States Congresses (March 4, 1799 – March 3, 1801), after being defeated in the 5th Congress by
James Cochran. He was also a candidate for the same seat in 1793. In 1796, Cooper determined to make his home permanently in the town he had founded, which by that time promised to become a thriving settlement. It attracted many land-hungry migrants from New England. He began the construction of a mansion, completed in 1799, which he named
Otsego Hall. For many years it served as his
manor house; it was by far the most spacious and stately private residence in central New York. In the first decade of the 1800s, Cooperstown began to struggle financially and saw a significant increase in violent crime, with Cooper himself being caned in the streets in 1807. Cooper family tradition has it that Judge Cooper was killed by a blow to the head sustained during an argument with a political opponent after a public meeting in
Albany, New York on December 22, 1809. No evidence of this can be found, and the story appeared to arise in 1897. A great-grandson of the judge published this account, which historians consider implausible. They believe that Judge Cooper died of natural causes. Cooper was buried at the Episcopal Christ Churchyard in Cooperstown. His son
James Fenimore Cooper, a popular author of historical novels, was buried there many years later. A great-grandson,
Paul F. Clark, became a
Nebraska State Representative. A great-great-grandson, writer
Paul Fenimore Cooper, is known for the children's adventure,
Tal: His Marvelous Adventures with Noom-Zor-Noom (1929, reprint 1957 and 2001). ==Legacy and honors==