Titusville is a hamlet and census-designated place in the town of LaGrange, New York, in Dutchess County, United States. As of the 2020 census, it had a population of 729. Titusville is in the southwestern part of the town of LaGrange, 5 miles southeast of the city of Poughkeepsie. It is bordered to the south by the hamlet of Red Oaks Mill. According to th…Titusville is a hamlet and census-designated place in the town of LaGrange, New York, in Dutchess County, United States. As of the 2020 census, it had a population of 729. Titusville is in the southwestern part of the town of LaGrange, 5 miles southeast of the city of Poughkeepsie. It is bordered to the south by the hamlet of Red Oaks Mill. According to the U.S. Census Bureau, the Titusville CDP has an area of 0.69 square miles, all land.