1940-1949

All building materials were made fire-resistant to protect against incendiary bombing. Treatment involved a vacuum process of salt impregnation. During construction, high winds caused a partial collapse of some members. The ruined materials were piled for incineration, but would not burn; so the rubble was buried on site. Years later, a farmer leasing ground on the site plowed up some of the materials. They were reported to still be in good condition.

With its landscaped embankments, limited access, and depressed roadway, Arroyo Seco Parkway (now known as the Pasadena Freeway) became the prototype of the Los Angeles freeway system. Motorists enjoy a scenic drive featuring landscaped embankments lush with native chaparral. The curving alignment traverses a chain of small parks shaded by sycamores and eucalyptus and exposed views of the snow-capped San Gabriel Mountains.

The Alaska Highway, initially called the Alaskan-Canadian (Alcan) Military Highway, provided an essential transportation link to the Yukon and Alaska during World War II. It begins at the junction with several Canadian highways in Dawson Creek, British Columbia and runs to Delta Junction, Alaska, via Whitehorse, Yukon. After the shock of Pearl Harbor, the Alaska Highway was a first step in America's defense strategy -- a vital military supply line during the war. Over ten thousand Army Engineers were rushed to the far Northwest.

The refrigeration units placed on trucks in 1938 by Thermo King Corp. revolutionized the transportation of perishable foods. Today they are a common sight on streets everywhere. Consumer demand for meat, poultry, produce and dairy products increased at an astounding rate. These installations and subsequent ones on refrigerated vehicles, ships, and railroads have had worldwide impact on the preservation of food and other perishables during distribution.

The articulated wheel-base steam locomotive represents the final phase of steam locomotive development in size and power. The cab-in-front feature was widely used by the Southern Pacific Railroad beginning in 1909 to alleviate smoke and heat problems for locomotive personnel en route through tunnels and snow sheds. This locomotive, built by the Baldwin Locomotive Works, operated between 1944 and 1956 before being displaced by a diesel-electric locomotive.

The 4,620-horsepower GG1 was primarily a passenger locomotive, routinely operating at over 100 miles per hour, but was used in freight service as well. Conceived by the Pennsylvania Railroad and built by the Baldwin Locomotive Works and General Electric Company, No. 4800 logged nearly 5 million miles in its forty-five-year life. It was the prototype for a 139-unit fleet built during a decade to serve on the PRR's electrified lines, and the only one with a riveted body shell; the remainder were welded.