USA

The Chesapeake & Delaware Canal is the only canal built in 19th-century America that still operates today as a major shipping route. Connecting the Port of Baltimore and Upper Chesapeake Bay with the mouth of the Delaware River and the Port of Philadelphia, the canal was one of the first civil engineering projects proposed in the New World and one of the most difficult to carry out. Although only 14 miles long, the canal's original cost made it one of the most expensive canals ever built in America.  

The Cheesman Dam was the first major dam in the U.S. to incorporate the gravity arch, and upon completion it was the highest gravity arch stone masonry dam in the world. It is the key structure in Denver's water supply.

Three years into original construction, flooding swept away the partially completed rock-filled structure. A solid masonry replacement dam was completed in just five years - a major feat for such a remote and complex project. When it was finished, the dam rose higher than the tallest building in Denver. 

The Carrollton Viaduct over Gwynn's Falls was the first masonry railroad viaduct constructed in the United States. This structure proved the feasibility of using a viaduct to transport railway vehicles across wide and deep valleys.

The William H. Chandler Chemistry Laboratory was conceived and planned by William Henry Chandler (1841-1906), professor, chairman, librarian, and acting president of Lehigh University. Designed by Philadelphia architect Addison Hutton and erected between 1884 and 1885 at a cost of $200,000, the building set the standard for laboratory construction for the next half century.

Clarifying the turbid waters of the Mississippi River for use as drinking water was a formidable challenge. The Chain of Rocks Water Purification Plant provided the first application of a system of flocculation, sedimentation, and rapid sand filtration for water purification.

The system played a major role in reducing the impact of St. Louis' typhoid and cholera epidemic of 1903 that claimed 287 lives. Continued improvements to the plant reduced that number to 91 by 1914. It is estimated that 1,900 lives were likely saved between 1903 and 1915 due to the filtration system.

Requests for public power in Seattle began in the late 1890s and lead to the voter approval for building the Cedar Falls Water Supply hydroelectric dam plant in 1902. The first municipally developed and owned hydroelectric plant in the United States began operation in October 1904. The facility is situated one-half mile below Cedar Lake (later known as Chester Morse Lake) near North Bend in King County. 

In 1894, Catawba County, North Carolina commissioners asked local landowners to build and maintain an 85-foot-long bridge across Lyles Creek. The community hired Andy L. Ramsour, who served as keeper of the Horseford covered bridge over the Catawba River in Hickory, North Carolina.

The fort was constructed of coquina rock. Unique to Florida, the rock consists of millions of seashells cemented together. It proved highly durable and easily absorbed the force of many cannon balls. 

The Castillo de San Marcos was the first permanent European settlement in the continental United States. Originally an outpost of the Spanish Empire, it is the oldest major engineered structure existing in America.

The Atlantic Ocean's northward-flowing Gulf Stream meets the southward-flowing Labrador Current at a point marked approximately by North Carolina's Outer Banks. Since the earliest days of United States commerce, shifting tides, inclement weather, treacherous shoals, and a low-lying shoreline there contributed to what soon became known as the Graveyard of the Atlantic. Warning sailors of this danger quickly became a top priority in the integrated system of navigational aids provided by the federal government to promote safe passage along the Atlantic Coast.