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Asphalt is the most common paving material used in the United States. It was not always that way. Cobblestones were used in colonial times across the east. They were relatively inexpensive and readily available. However, they were dangerous and difficult for both horses and pedestrians to travel on. Granite blocks were also used and had a smoother surface. They were expensive to lay, slippery when wet, and noisy with horse and wagon traffic. In about 1870’s fired brick begin to catch on as a paving material. However, the relatively soft bricks did not hold up under traffic. Brick makers learned to produce dense, vitrified brick that resisted abrasion. Like granite, brick had the disadvantages of being slippery when wet and noisy.
In the latter half of the nineteenth century many communities tried to give their streets a more durable surface. They spread coal tar over Macadam roads, which did improve the ability of the streets to shed surface water. Coal tar coated streets still had many draw backs. It remained sticky long after it was spread, clogging horses hooves and pedestrians shoes. It was also easily rutted by vehicle wheels.
Macadam roads were popular as self-draining roads, being made of one-inch crushed stone laid ten inches deep. However, their construction was expensive. The major factor being the labor to create the angular crushed stone. It took one man 2 days to crush a cubic yard of stone by hand. In response to the volume of crushed stone needed Eli Whitney Blake developed a steam-driven mechanical stone crusher in 1832.
By the last decade of the century Asphalt became a more promising material for paving. The first really significant use of Asphalt appears to have been in 1721, when a rock asphalt deposit was discovered at Val de Travers in Neuchatel Canton in Switzerland. Val de Travers asphalt was first laid on a concrete foundation in Paris in 1838. While this first asphalt paving was reasonably successful it was also slippery when wet. By 1867 it offered so many advantages that the French began tearing up their cobblestone and granite block streets to replace them with the new asphalt.
 Word of the success of asphalt pavements in Paris soon reached New York, where the civic authorities in 1869 decided to put an asphalt topping over the granite-block paving of Fifth Avenue. One of the showplace boulevards of the city, lined with the mansions of many of its wealthiest citizens. Property owners had long complained about the noise of hooves and wagon wheels on the granite surface, and the frequent accidents involving horses unable to keep their footing. The methods and materials used on Fifth Avenue were not the same as used in Paris and the new asphalt failed within 3 weeks. Workmen were continually patching the Avenue. Soon New Yorkers were demanding that the asphalt be removed. At the time contractors in the United States lacked the knowledge and experience required to lay asphalt with assurance of success.
Asphalt paving was finaley met with success in Washington, D.C. President Grant nudged the municipal authorities to replace the deteriorating wood-block paving with asphalt. Congress proceeded with caution and hired the Army Corps of Engineers to supervise the project. Most of the work was done by the Barber Asphalt Paving Company. During the 1880s the District paved about seventy miles of streets with Trinidad Asphalt and success.
The Barber Company was founded in 1883 by Amzi L. Barber, a onetime professor at Howard University who observed the asphalt paving in Washington and decided to go into the business himself. Barber developed a reputation for quality work. He secured contracts in many other U.S. Cities inspired by the Washington, D.C., success.The Barber Company became a highly organized and capable organization. By 1898 it laid twenty-four million square yards of paving on 1500 miles of streets in more than a hundred cities.
Increasing demand by U.S. cities for paved streets and roads led growing numbers of contractors to enter the asphalt business. Cities offering paving contracts would often attract five or six bidders, but few of these had much experience. Contractors had to feel their way with the material, adjusting to the different characteristics of asphalts from different deposits, and failures were frequent. Only slowly did contactors and city engineers come to realize that asphalts from different locations were not all the same. Techniques that succeeded with material form one source might fail when used with asphalt from a different deposit. One of the earliest to explain this was E.B. Ellice-Clark, who observed that asphalt was a generic term for bitumen mixed with many other materials in varying proportions, including small quantities of mineral tar similar to residue from distilled coal and shale oils.
Sources of technical knowledge began to proliferate. In 1890 the University of Pennsylvania offered cash prizes for papers on road building. The Case School of Applied Science began to offer courses on the subject for engineers and contractors. Harvard University and the Massachusetts Institute of Technology followed.
 With many requests for federal aid to road building, Congress authorized the creation of an Office of Road Inquiry (ORI) within the Department of Agriculture in 1893. By 1896 the Hetherington and Berner Company of Minneapolis and a few other firms had developed portable asphalt plants, mounted on railroad flat cars, that could move to any town on a rail line. Just at this juncture steam rollers were developed by the firm of Aveling and Porter in England and became available in the United States. The appearance of automobiles in the latter years of the century gave an important impetus to the ORI. As automobilists articulated their interest in better highways, Congress responded with a thirty-five-thousand dollar appropriation for the ORI in 1905. That same year the name of the Office of Road Inquiry was change to Office of Public Roads (OPR). By 1907 appropriation funds had risen to seventy thousand dollars.
The Office of Public Roads Laboratory in Washington, D.C., was created to develop a greater scientific precision in road building. Geologist Logan W. Page moved to Washington to head the new organization. The new laboratory immediately began to have an influence. Page and his staff also engaged in research and the Laboratory actually developed the standards for asphalt.
The knowledge base of information on asphalt and the techniques for applying it successfully expanded rapidly after 1900. The knowledge base was also becoming more scientific. By 1915 the American Society for Testing Materials published a series of reports setting standards and describing the merits of a wide range of road building materials.
The Asphalt Association was formed in 1919 to disseminate information on the uses of asphalt. One of the first moves taken by the Asphalt Association was to establish a research and testing division. The association recruited Prevost Hubbard, who had previously headed the laboratory in the Bureau of Public Roads and was the author of an influential book on bituminous materials. In 1919 the United States produced six hundred thousand tons of asphalt valued at approximately nine million dollars. By 1923 the nation was producing over a million tons a year. In the decades that followed World War 1 technological innovations continued with machinery and remarkable advances in the chemistry of Asphalt. Asphalt was showing its superiority over other road building materials.
By the turn of the twenty-first century, more than 90 percent of all pavements in the United States were asphalt. Asphalt is now the most common paving material in the United States.
{Excerpts from the book, "BLACKTOP - How Asphalt Paving Came to the Urban United States," by I.B. Holley, Jr., Department of History, Duke University)
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