Task: Question Generation
Input (English): Passage: Following the Seven Years' War (1756–63) and the forced migration of Native American tribes westward, German, Scots-Irish, and other European immigrants settled in the central Susquehanna Valley, including in the area that would become Northumberland, Pennsylvania. Northumberland was laid out around a central village green in 1772, on land originally purchased from the Iroquois by the Province of Pennsylvania in 1768, as part of the first Treaty of Fort Stanwix. During the American Revolution, the village was evacuated as part of the Big Runaway in 1778, and only finally resettled in 1784. In 1794, when the Priestleys moved there, it included Quaker and Wesleyan meeting houses, a brewery, two potteries, a potash manufacturer, a clock maker, a printer (who issued a weekly newspaper), several stores, and approximately one hundred houses.
The Priestley property, purchased in 1794 at a total cost of £500 (£ 56,400 in 2019) from Reuben Haines, who had secured the patent to the land for Northumberland, comprised four lots of the original village plan (numbers 29–32). Currently, the house and grounds occupy 1 acre (4,000 m²) at 472 Priestley Avenue. (The address of the house was originally "North Way", but the street was later renamed in honor of Joseph Priestley.) This street forms the northwest boundary of the property; the other boundaries are Hanover Avenue to the northeast, Wallis Street to the southwest, and the North Shore Railroad to the southeast. Beyond the railroad line is a baseball field, and beyond that lies the Susquehanna River, which was the original southeastern boundary of the property. The confluence of the West Branch Susquehanna River with the main (or North) branch of the Susquehanna is a short distance southwest of the property, which is at an elevation of 456 feet (139 m).The property's original area was 2 acres (8,000 m²), but this was reduced by about half around 1830 when the Pennsylvania Canal (North Branch Division) was dug through the house's front yard, between the house and river. On May 31, 1860, the Lackawanna and Bloomsburg Railroad opened with a train from Danville. This was the second railroad track in Northumberland, and ran behind the house. The canal closed in 1902 and was later filled in. The modern railroad line approximates the canal's course through the front yard; the track behind the house no longer exists.
Output (English): What was reduced from 2 acres to 1 when the Pennsylvania Canal was dug?