127 passengers and/or crew members. In the 1950s, the city limits were about six square miles, but by 1960, the city had its single largest year in geographical expansion in Naperville's history. That year saw over 1,500 acres annexed. In 1955 Edward Sanatorium was converted into a general hospital. A predominantly rural community for most of its existence, Naperville experienced a population explosion beginning in the 1960s and continuing into the 1980s and 1990s. Throughout the 1990s and '80s the city's population tripled. In 1996, Naperville was the site of a flood that also affected the majority of northeastern Illinois. Naperville received 14 inches of rain in less than 24 hours, and DuPage County was declared a disaster zone. The estimated damages were over $30 million. The YMCA in Downtown Naperville was announced to close in May 2020 after 109 years of operation, due to economic difficulties caused by the COVID-19 pandemic. Geography According to the 2021 census gazetteer files, Naperville has a total area of , of which (or 98.52%) is land and (or 1.48%) is water. Parts of Naperville drain to the West Branch of the DuPage River in DuPage County. The Forest Preserve District ownership of a large amount of property along the West Branch has minimized development in floodplains and has helped reduce the damage from overbank flooding that has occurred in the county's more developed watersheds. The DuPage River Trail also runs along the DuPage River, which serves bikes and pedestrians. Naperville was primarily flat prairie before its settlement. Its main geographic anomalies are manmade hills, such as the Greene Valley Hill, a former garbage dump. Naperville has had two major floods, one in 1996 and one in 2013. Naperville is in six townships and two counties. In DuPage County, the northwest portion is in Winfield Township, the northeast portion in Milton Township, the west-central portion in Naperville Township, and the east-central portion in Lisle Township. In Will County, the southwest portion is in Wheatland Township and the southeast portion in DuPage Township. The largest number of Naperville residents live in Lisle Township, followed by Naperville Township. Naperville's municipal boundaries are cut in noticeably by many places. In the west, Springbrook Prairie, a forest preserve run by The Forest Preserve District of DuPage County, is a major enclave. In the southwest, the Tamarack neighborhood is a major unincorporated enclave. In the north, McDowell Grove Forest