1977

Minot's Ledge is a wave-swept rock formation in a rocky area of ocean about a mile off the Cohasset shore near Boston. Numerous serious shipwrecks prompted the government to erect a beacon there, and construction began in the summer of 1847.  

The light, constructed on tall iron legs, was put into operation on January 1, 1850. Designers believed that the water would flow freely through the legs, leaving the lighthouse intact. But a terrible winter storm toppled it in 1851, killing the two assistant keepers.  

The granite milestones marking the Mason-Dixon Line bear crests from the two parties involved in the land-grant dispute, the families of William Penn and Charles Calvert (also known as Lord Baltimore). 

At a time when steam power was finding its first uses in America, Philadelphia opened two steam pumping stations, January 1801, to lift water from the Schuylkill River and distribute it through the city's wooden pipes and mains. By 1811 a new water power works was begun on the river near Morris Hill, and the Fairmount Water Works opened September 7, 1815. These water works represented the first large-scale application of steam pumping to water service in the country.

Designed by Sam Diescher, son-in-law of the Monongahela's designer John Endres, the Duquesne Incline opened May 20, 1877, as the second of seventeen built and operated in the Pittsburgh area. It has operated with only minor interruptions for the last one hundred years. A preservation group from Duquesne Heights and Mount Washington interceded in 1962 to refurbish this incline to working order. Like the Monongahela, the Duquesne was steam powered and then converted to electric and updated with modern safety devices.

Visionary Alexander Hamilton, the United States' first Secretary of the Treasury, visited the Great Falls of the Passaic River with George Washington in 1778. The 77-foot-high, 280-foot-wide waterfall inspired his dream of abundant, inexpensive energy as the means for economic independence from foreign markets.