The Hempstead Plains is a region of central Long Island in New York state in what is now Nassau County. It was once an open expanse of native grassland estimated to once extend to about 60,000 acres (240 km2). It was separated from the North Shore of Long Island by the Harbor Hill Moraine, later approximately the route of Route 25. The modern Hempstead Turnpike approximately traces the separation of the plain from the South Shore of Long Island. The east-west extent was from somewhat west of the modern Queens, New York City border to slightly beyond the Suffolk County border.
The Town of Hempstead, now America's most populous civil township, was first settled by Europeans around 1644. Although the settlers were from the English colony of Connecticut, a patent was issued by Dutch New Amsterdam after the settlers had purchased land from the local Native Americans. The town may have been named for either Hemel Hempstead, England, or the city of Heemstede in North Holland.
In early US history, the Hempstead Plains region was cited as one of the few natural prairies east of the Allegheny Mountains. Long Island historians George Dade and Frank Strand wrote that it was created by an outwash of glacial sediment more than ten thousand years ago. The result was vast, flat open land.