At the same time that MacDonald was cranking up his vast technocratic machine, others were developing huge new machines capable of building the new roads. Until the end of the nineteenth century, road builders relied upon teams of horses and wagons to move earth and rock. In 1887, at the St. Leandro Plow Works in California, Daniel Best, a 49 year-old farmer and inventor, had the idea of that a steam engine attached to wheels could be used for logging, ploughing, and earth moving. Steam on the farm was not new, nor were steam engines on wheels. Best himself had built some, and would build a colossal combine with wheels 15 feet wide and 9 feet in diameter that could do little more than go in a straight line. His new steam engine driven machine of 1887 was different. He reduced its size and gave it large wheels to go through the deep earth of farmers' fields. Best called his creation a "traction engine." Others called it a tractor. Best's tractor quickly gained in popularity, but soon he had a formidable rival.

In 1890, in nearby Stockton, California, Benjamin Holt, a forty-one year old builder of farm machines and compulsive tinkerer, created his own steam traction engine. Over the next 24 years he turned out 130 more, including a miniature model for the King of Spain. But the large, wide wheels of Best's and Holt's tractors proved their greatest liability. Farmers found that no matter how great the width the wheels were, the machines sunk in the rich California soil. Holt set to tinkering. In 1904 he replaced the wheels on his traction engine with a smaller set that turned an endless steel band of movable self-laying tracks. These, he found, distributed the machine's weight over a broad path and made it far more agile on rough ground, too. "In a tract where a man could not walk without sinking up to his knees," reported the Farm Implement News, "the new traction engine was operated without a perceptible impression in the ground." Because of the way it moved across the landscape, Holt called his new machine a "Caterpillar" tractor. While Holt was busy developing his caterpillar tractor, Daniel Best had not been idle. By 1895 he had developed a gasoline-powered engine for his tractor, thereby lowering the risk of fire and eliminating the need for water, a boiler and a fireman. In 1908 at age 70, Best decided to retire and sell his company to his old rival, Benjamin Holt, who moved the new company east to Peoria, Illinois.

Just what Clarence Leo Best, Daniel's son who was a superintendent at his father's company, thought of the sale is unknown, but he did not join Holt in the new company. In 1910 he organized the C. L. Best Gas Traction Company and introduced his own caterpillar-type tractor. For fifteen years the two companies competed for much of the same business. Each had its strengths. The Holt company sold many of his machines in foreign countries, while Best had developed a network of dealers in the United States. Finally, in 1925, after Benjamin Holt's death, Clarence Leo Best decided to merge with his former rival's company. Best became Chairman of the Board of the new venture, the Caterpillar Tractor Company. The movement from horses to steam, and then to gasoline, was gradual. Over the years men wielding shovels and pick axes and driving horse-drawn wagons yielded to power shovels and dump trucks. Engineers began using bulldozers--powerful track type machines with large blades for pushing the earth--along with large power shovels. Together the bulldozers and power shovels could make cuts and grades more efficiently. The cost of moving a cubic yard of earth declined from 40 cents in 1922 to 21 cents in 1938.

In its 1916 Road Act, Congress funded the federal road program with 75 million dollars for five years; in its 1921 Federal-Aid Highway Act it funded federal roads with 75 million dollars a year. By the end of the decade the Bureau of Public Roads would spend 750 million dollars. In addition to giving the Chief and his Bureau more money to distribute to the states, the 1921 act made real the idea of a national road system. Each state would designate seven percent of its roads to be linked with those in other states. Linking all the county seats in the country, these primary routes would create, MacDonald wrote in his best bureaucratic style, a "complete and economical highway transport service throughout the nation." They were, he said, "interstate." Armed with the 1921 Highway Bill, MacDonald and the Bureau of Public Roads coordinated with each state the designation of federal interstate roads so that they would correlate at each state's borders. They completed the task by the end of 1923.

The Bureau asked AASHO to create a uniform numbering system for federal interstate routes, to simplify traveling directions for motorists. AASHO in turn named MacDonald to chair the committee. Under the Chief's direction the committee designated north to south routes with odd numbers beginning with "1" on the east coast and "101" on the west, and east to west routes with even numbers beginning with "2" across the top of the country and "70" across the bottom. By October 1925 the scheme was in place and federal shields emblazoned with route numbers began to appear on federal interstate roads around the country. As Congress produced the money, MacDonald produced the miles. "Without overstatement," the Chief wrote in his annual report, "it may be said that greater progress has been made in providing the means of highway transportation during the fiscal year 1922, than in any similar period in the history of the country." He was right. With his Bureau's assistance, states had added 10,000 miles, "something more than the equivalent of three transcontinental roads," to the Federal-Aid highway system. State highway departments in the east usually used concrete or asphalt, while in the west, where traffic was light, workers graded the surface, solved drainage problems, and put down gravel or sand-clay. The results were often dramatic. Engineers redesigned the road between Ariton and Clayton, Alabama, two small towns southeast of Montgomery, to eliminate thirteen of fourteen railroad crossings. On the road from Baltimore to Washington they eliminated a curve that over the years had accounted for the loss of 35 lives.

Although the initial impact of a road project was always local, it usually fit into a larger scheme of the binding of the nation in a web of interstate highways, a design "no less important to the country...than that offered by the railroads." At the moment, highway transportation was still intermittent. But the day would come when it was continuous. My aim is this," MacDonald said in 1924. "We will be able to drive out of any county seat in the United States at thirty-five miles an hour and drive into any other county seat--and never crack a spring." As the nineteen twenties continued, MacDonald's highway machine operated with superb precision. Speakers from the Highway Education Board continued to tell children at school assemblies about the myriad ways good roads would improve their lives and help America grow. Civic groups showed the latest good roads film, often produced by an automobile manufacturer in cooperation with the Bureau of Public Roads. Statisticians in the Highway Research Board ground out reports on traffic flow and "desire lines"--those roads Americans used most frequently. And most important AASHO officials from each of the 48 states connected with their senators and representatives to insure Congress continued to vote more money for highway projects. By any measure MacDonald's achievement in the twenties was impressive. In just one year, 1927, the Bureau of Public Roads was responsible for the construction of 10,220 miles of new roads costing 84 million dollars in federal and 105 million dollars in state funds. By the end of the decade, the Chief and his Bureau were responsible for over 90,000 miles of federal-aid highways, and were expending an average of 78 million dollars each year.

Given this size and efficiency of the highway machine it was no wonder MacDonald developed a sense that it was his destiny to lead America to highway greatness. "There have been just three great programs of highway building within recorded history" he told the annual meeting of the American Association of State Highway Officials, in 1926, "that of the Roman Empire, beginning with Julius Caesar and extending to Constantine; that of France under the Emperor Napoleon; that of the United States during the last decade." The first two, he noted, were conducted under the rule of despots. Only the United States has produced a comprehensive system under democratic rule. In MacDonald's mind the economic well being and therefore the success of democracy and freedom depended upon federal construction of roads that, by a stipulation in the first paragraph of the 1916 Federal-Aid Road Act, would be "free from tolls of all kinds." The power of MacDonald's machine was such that few in state legislatures resisted this logic and the money that flowed from the Bureau of Public Roads. The reins upon the growing trucking industry remained loose. Roadside strip development and bill boards grew without control. With the federal government paying fifty percent of construction costs, few states thought of building toll roads. Anyone who suggested regulations or tolls, threatened, MacDonald said, "freedom of the road."