They called the region Lenapehoking, which consisted of the area around and between the Delaware and Hudson Rivers. Several different tribes occupied the area, including The Manhattans, and the Weckquaesgeek and Siwanoy bands of the Wappinger in the south, and Tankiteke, Sintsink and Kitchawank Wappinger in the north. The first European explorers to visit the Westchester area were Giovanni da Verrazzano in 1524 and Henry Hudson in 1609. Dutch settlers began arriving in the 1620s, followed by settlers from England in the 1640s. Westchester County was one of the original twelve counties of the Province of New York, created by an act of the New York General Assembly in 1683. At the time it included present-day Bronx County, and abutted then-Dutchess County to the north. By 1775, Westchester was the richest and most populous county in the colony of New York. Although the Revolutionary War devastated the county, recovery after the war was rapid. In 1788, five years after the end of the war, the county was divided into 20 towns. In 1798, the first federal census recorded a population of 24,000 for the county. Two developments in the first half of the 19th century—the construction of the first Croton Dam and Aqueduct, and the coming of the railroad—had enormous impacts on the growth of Westchester. The Croton Dam and Aqueduct was begun in 1837 and completed in 1842; now a National Historic Landmark, the Croton Aqueduct is considered one of the great engineering achievements of the 19th century. In the 1840s, the first railroads were built in Westchester, and included the New York and Harlem Railroad, the Hudson River Railroad, and the New York and New Haven Railroad. The railroads often determined the growth of a town, and the population shifted from Northern to Southern Westchester. By 1860, the total county population was 99,000, with the largest city being Yonkers. The period following the American Civil War enabled entrepreneurs in the New York area to create fortunes, and many built large estates, such as Lyndhurst, in Westchester. During the latter half of the 19th century, Westchester's transportation system and labor force attracted a manufacturing base, particularly along the Hudson River and Nepperhan Creek. In 1874, the western portion of the present Bronx County was transferred to New York County, and in 1895 the remainder of the present Bronx County was also transferred to New York County.