Civil

The stone was set by the joint U.S.-Spanish survey party on April 10, 1799.  Made of sandstone, it is roughly two feet high and eight inches thick. On the north side of the stone is the inscription "U.S. Lat. 31, 1799." On the south side is "Dominio de S.M. Carlos IV, Lat. 31, 1799."

The Wheeling Suspension Bridge was the first bridge to span the Ohio River. It was initially completed in 1849, but destroyed by a tornado five years later. The bridge was rebuilt in 1856. The replacement bridge has the same general appearance of the original structure; the massive towers, anchorage housings, and island approach are all the original stone masonry.

One of the first major efforts to increase farming and encourage habitation in the arid regions of the western United States, the Rio Grande Project was designed to provide reliable irrigation as well as resolve a dispute over water supply with the Republic of Mexico.  The project's centerpiece is Elephant Butte Dam, a concrete gravity structure 301 feet high and 1,674 feet wide. Elephant Butte Reservoir - with a surface area of 36,600 acres and a capacity of more than 2.2 million acre-feet - was the largest reservoir in the world at the time of its completion.

An early image of the James Douglass lighthouse, with the stump of the Smeaton-designed building beside it.  

Eddystone Lighthouse is located in the English Channel, 14 miles south of Plymouth, England. The reef upon which it stands was the source of many shipwrecks... and many lighthouses, the first of which was built in 1698. The first three lighthouses were wooden, and suffered the fate of sea storms. John Smeaton  built the fourth lighthouse in 1759 of Cornish granite.   

Inventions credited to the Ecole Nationale des Ponts et Chaussees and its graduates include: prestressed concrete, lighting gas, and the optical lens. The school and its graduates also have been central to research in the diffraction of light, the applications of concrete, and the measurement of the strength of materials.

In the decade following the Civil War, the Mississippi River began to lose its standing as the primary transport artery in the Midwest. Railroads were taking over, and Chicago was rapidly becoming the center of Midwestern commerce. The Eads Bridge was the first major railroad link over the Mississippi, constructed by the city of St. Louis in an attempt to maintain its dominance as a regional commercial hub.

The Durango-Silverton Narrow Gauge Branch of the Denver & Rio Grande Western Railroad extends from the town of Durango to the mining camp of Silverton. Built in 1882 through one of the most rugged mountain areas of the nation, its complexity remains a testament to the role civil engineering played in the development of the western United States. 

The tracks rise up the sheer, steep Animas Canyon, running along a rock ledge just wide enough to carry the train. The line is used today as a tourist attraction, carrying visitors through the picturesque San Juan Mountains.

Not only was Dunlap's Creek Bridge the first cast-iron bridge in America, it was the first metal bridge anywhere to use what its builder, Capt. Richard Delafield, U.S. Army Corps of Engineers, described as "standardized, interchangeable, manufactured parts." The bridge was built as part of the federal government's effort to make repairs on the National Road  before handing authority over to the states. Dunlap's Creek at Brownsville was an especially troublesome crossing, having destroyed three previous bridges since 1801.

The significance of the 15-mile Whitewater Canal was not in its ability to create a profit, but rather its effect on the economic growth of the Whitewater River Valley, considered the gateway to the interior of Indiana. Before the canal, travel was challenging. Most waterways in Indiana were only navigable by canoe, and the alternative - horse and wagon - was difficult, slow and expensive.  

Like other American cities in the late 19th century, Baltimore had grown so quickly its supply system was unable to provide city residents with a dependable supply of water. Two reservoirs built outside the city helped increase capacity, but heavy rainfalls in the largely agricultural area tended to foul this additional water supply. City officials elected to construct a holding reservoir within the city - contained by an earthen dam - where silty water would be allowed to settle. No such project had ever been undertaken in the United States.