USA

The crossing of the Delaware River at Easton, Pennsylvania, provided a central link in travel from the northeastern seaboard to America's inland territories throughout the 18th and early 19th centuries. From 1806 to the mid-1890s, travelers used a landmark wooden structure built by noted bridge-builder Timothy Palmer. By the 1880s, however, Palmer's three-span covered bridge could no longer handle the demands of traffic generated by new trolley lines.

The Northern Pacific High Line Bridge No. 64, built between 1907 and 1908, has continued to perform yeoman service in the uninterrupted flow of the Nation's commerce. Nearly, 100 years after this bridge officially opened, it still carries 125-ton car unit coal trains, double stack container trains, lumber, and refined products at train speeds of 50 m.p.h.

Norris Dam impounds the Clinch River, a mountain tributary of the Tennessee River. The facility stands as a tribute and symbol of the birth of the Tennessee Valley Authority (TVA). Given broad jurisdiction over resource development in the watershed (a 40,000-square-mile basin comprising parts of Virginia, North Carolina, Georgia, Alabama, Mississippi, Kentucky, and Tennessee), the TVA was formed to plan for flood control, improve navigation, and produce hydroelectric power.

This machine, designed by Alton S. Newell, efficiently reduced automobile bodies into scrap metal for recycling. A body was fed into the shredder at a controlled rate, and rotating hammers, driven by a 500-hp motor, shredded it into small pieces that were easily shipped. The process took about 10 minutes a car and used less energy than other shredding and crushing machines. 

In May 1927, the same month of Charles A. Lindbergh's famous transatlantic flight from New York to Paris, a fact-finding commission appointed by the U.S. Secretary of Commerce concluded that Newark would be the ideal location for an airfield to serve the greater New York/New Jersey metropolitan area.

Civic leaders wasted no time; construction began on the Newark Airport in January 1928. Nine months and $1,750,000 later, 68 acres of soggy marshland had been filled and converted to an airport.

In 1794, the Delaware legislature authorized a lottery to fund the erection of ice piers in the harbor at New Castle. The ice harbor was designed to protect anchored ships from storms and ice. At the time, New Castle served as the principal winter port for ships from the Port of Philadelphia because ice on the Delaware River posed such a serious hazard to the wooden-hulled vessels. The harbor was the first of its type on the river and the last one to be maintained as the need for them declined. It served as a model for the other four harbors constructed in the area.

Navajo Bridge spans Marble Canyon, 470 feet above the Colorado River in Grand Canyon National Park. It was considered the highest steel arch bridge in America when completed.

The Navajo Bridge (also known as the Grand Canyon Bridge) was built in 1929 by the Arizona Highway Department and provided a vital transportation link over the Grand Canyon between northern Arizona and southern Utah. Construction commenced by building on one side of the canyon, then on the other, until the two sides met in the middle.

The National Road was the first interstate highway in the United States, and the first roadway to be financed with federal money. Authorized by Congress during the administration of Thomas Jefferson in 1806, the road was built over time and in sections from Cumberland, Maryland, westward through the states of Pennsylvania, Virginia (now West Virginia), Ohio, and Indiana, before terminating at the state capital of Vidalia, Illinois.