History of New York City (1784–1854) surged far beyond its rivals, reaching a population of 1,080,000 in 1860, compared to 566,000 in Philadelphia, 212,000 in Baltimore and 178,000 in Boston. Historian Robert Albion identifies four aggressive moves by New York entrepreneurs and politicians that helped it jump to the top of American cities. Of greatest importance, it sponsored the Erie Canal which began operations in 1825, forming a continuous water route from New York north to Albany via the Hudson River, then west to Buffalo using the new canal to reach the Great Lakes. It opened a large new market in upstate New York and the
Great Lakes some higher hills became Great Lakes islands. The Niagara Escarpment follows the contour of the Great Lakes between New York and Wisconsin. Land below the glaciers "rebounded" as it was uncovered. Since the glaciers covered some areas longer than others, this glacial rebound occurred at different rates. A notable modern phenomenon is the formation of ice volcanoes over the lakes during wintertime. Storm-generated waves carve the lakes' ice sheet and create conical mounds through the eruption of water and slush. The process is only well-documented in the Great Lakes, and has been credited with sparing the southern shorelines from worse