Known as "the highest and lowest holing in history," the tunnel bored through the Rockies at an elevation of 9,200 feet, 2,800 feet below the surface. Eight hundred men worked around the clock for 3 1/2 years, moving 3 billion pounds of rock.
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.
This was America's first large-scale activated sludge plant. The successful operation of Milwaukee's sewage treatment plant led the way for many other American municipalities to adopt its methods of efficient environmental recycling.
Prior to 1925, sewage and industrial waste from the City of Milwaukee and its suburbs (then population 500,000) was discharged to the Milwaukee, Menomonee, and Kinnickinnic rivers, which converge in Milwaukee and flow together through a single outlet into Lake Michigan.
In 1794, Congress authorized and President Thomas Jefferson signed into law the raising of a Corps of Artillerists and Engineers (now the United States Army Corps of Engineers) to be educated and stationed at the newly created United States Military Academy. The U.S. Military Academy was the first school of engineering in America to offer formal instruction in civil engineering.
While the Erie Canal has become well-known in the annals of American history, the Middlesex Canal, built two decades earlier and a model for canal engineers throughout young America, has only recently become recognized for its important achievements. Extending 27 miles northeast from Boston harbor to the Merrimack River near present-day Lowell, Masachusetts, the Middlesex Canal provided low-cost and efficient freight transport for almost five decades, helping to establish the canal in the U.S. as a viable means of economic development.
The city of Shreveport could not justify the cost of building a water distribution system solely for the purpose of supplying potable water. It was a series of disastrous fires in the 1880s that galvanized support for a pumping facility that would provide ample water for firefighting.
The Rogue River Bridge was the most advanced concrete bridge in America when it was built. Distinguished bridge engineer Conde McCullough employed the techniques of Frenchman Eugene Freyssinet to create thin, graceful concrete arches for this seven-span structure.
Pre-compression of the concrete arch was achieved and, as a result of its success, pre-stressing became one of the hallmarks of American bridge building techniques.
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).
Designed by Claude A. P. Turner, a pioneer of reinforced concrete construction, the Marshall Building was constructed originally in 1906 as a five-story building. In 1911 the sixth floor of the building was added as per Turner's original design. This building is the oldest extant example of Turner's "mushroom" flat-slab system which transformed the design and construction of reinforced-concrete floors worldwide.
When opened in 1909, the 1,470 foot long main span of the Manhattan Bridge was the third longest suspension bridge span in the world, after the nearby Brooklyn and Williamsburg Bridges. The Manhattan Bridge has two 725 foot long suspended side spans for an overall length of 2,920 feet. The bridge deck is supported by 4 main cables of 20.75 inch diameter, each composed of more than 35,000 individual wires. The bridge deck is stiffened by four parallel trusses of 24 foot depth, hinged at the towers.