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Office of Public Roads
The Office of Public Roads (OPR) is established, successor to the Office of Road Inquiry established in 1893. OPR’s director, Logan Waller Page, who would serve until 1919, helps found the American Association of State Highway Officials and lobbies Congress to secure the Federal Aid Highway Program in 1916, giving states matching funds for highways. -
Asphalt manufactured from oil-refining byproducts
Gulf Oil, Texas Refining, and Sun Oil introduce asphalt manufactured from byproducts of the oil-refining process. Suitable for road paving, it is less expensive than natural asphalt mined in and imported from Venezuela. The new asphalt serves a growing need for paved roads as the number of motor vehicles in the United States soars from 55,000 in 1904 to 470,000 in 1910 to about 10 million in 1922. -
First highway paved with portland cement
The first highway paved with portland cement, or concrete, is built near Pine Bluff, Arkansas, 22 years after Bellefontaine, Ohio, first paved its Main Street with concrete. Invented in 1824 by British stone mason Joseph Aspdin from a mix of calcium, silicon, aluminum, and iron minerals, portland cement is so-named because of its similarity to the stone quarried on the Isle of Portland off the English coast. -
Wisconsin adopts road numbering system
Wisconsin is the first state to adopt a numbering system as the network of roads increases. The idea gradually spreads across the country and replaces formerly named trails and highways. -
MacDonald appointed head of federal Bureau of Public Roads
Thomas MacDonald is appointed to head the federal Bureau of Public Roads (BPR), successor to OPR. During his 34-year tenure he helps create the Advisory Board on Highway Research, which becomes the Highway Research Board in 1924 and the Transportation Research Board in 1974. Among other things, BPR operates an experimental farm in Arlington, Virginia, to test road surfaces. -
Yellow traffic lights
William Potts, a Detroit police officer, refines Garrett Morgan’s invention by adding the yellow light. Red and green traffic signals in some form have been in use since 1868, but the increase in automobile traffic requires the addition of a warning signal. -
Uniform system of signs
State highway engineers across the country adopt a uniform system of signage based on shapes that include the octagonal stop sign. -
Numbering system for interstate highways
BPR and state highway representatives create a numbering system for interstate highways. East-west routes are designated with even numbers, north-south routes with odd numbers. Three-digit route numbers are given to shorter highway sections, and alternate routes are assigned the number of the principal line of traffic preceded by a one.