History: In 1728 the heirs of William Penn opened lands west of the Susquehanna River for settlement. While German and English immigrants founded the town of York, Scots-Irish farmers came to clear land in the area that was to become Peach Bottom Township and Delta Borough. Although right to the land was contested by the colonies of Pennsylvania and Maryland the farmers persevered and were soon followed by tradesmen such as millers, blacksmiths and carpenters. After the Mason-Dixon Line settled the land question in 1767, settlements grew rapidly, as did the varieties of occupation. Commercial slate quarries, opening from 1835 on, proved an impetus for a wave of immigration from Wales. A road constructed north of the slate ridge led to the river and the Susquehanna and Tidewater Canal. By 1853 there were about 20 homes and businesses along this road, soon to be called "Main Street". On December 26, 1853, residents met at the local tavern to choose a name for their village. After considerable discussion of family names, a compromise was reached by referring to the Greek alphabet, and all agreed to the name "Delta". Town growth continued until, on June 24, 1880, Delta became an incorporated borough, covering about 200 acres. With railroad connections to York and Baltimore, a period of rapid growth followed. The "good old days" of Delta's prominence in the county date from 1890 to 1930. With some 500 workmen employed in 15 operating slate quarries, there were two banks, three hotels, a weekly newspaper, churches, physicians, a school through grade 12 and a town water system, with numerous shops along Main Street. Around World War II, Delta began to decline as a commercial hub. The slate industry lost its markets and the quarries gradually closed. Small local businesses were replaced by larger stores in other towns. Following a burst of activity in the 1960's and '70's when the Peach Bottom Atomic Power Station was under construction, Delta finds itself primarily a bedroom community, striving to maintain its peaceful hometown atmosphere into the 21st century. The borough's Main Street was listed on the National Historic Register in 1983, with 80 structures described as representing significant, unique and historically valuable architecture.