Like most enterprises in nineteenth-century America, rail-roads in the early 1800s were local affairs. The first trains served mainly to carry goods between towns that canals did not reach, so each region of the country built its own rail lines. As a result, rail gauges— the width between rails—varied widely. The tracks laid between Richmond and Memphis, for instance, used a five-foot gauge, while the gauges of the Erie and Lackawanna lines in New York were six feet wide. Those in the mid-Atlantic, such as the Baltimore and Ohio, used the gauge that was standard in England: four feet eight and a half inches wide. These variations made it exceedingly difficult to connect rail lines, which in turn effectively curbed the use of railroads to conduct commerce across regions.
During the Civil War, President Abraham Lincoln recognized that this balkanized rail system also hurt something else: the war effort. He wanted to transport military materiel and goods across the country by rail. So he proposed a standard track width of five feet for the planned intercontinental railroad. He later amended his proposal to four feet eight and a half inches, to match the gauges of the largest eastern railroads, backing a plan urged by rail barons who wanted to expand their lines and their industry. This standard gauge made it possible to connect lines, and led to an explosion of railroad building. The number of track miles tripled, to 90,000, between 1860 and 1880, and then more than doubled, to 190,000, by 1900. With that expansion came the growth of whole new industries that could only be born through interstate train travel—for example, the auto industry, which depended on steel from Pennsylvania, rubber from Ohio, and coal from West Virginia, all shipped and put together in Michigan. Lincoln’s idea of a common standard helped make the United States the world’s largest industrial power.
In some ways, the American elementary and secondary education system is undergoing a transition similar to what the American rail system underwent around the time of the Civil War. For decades, each state has set its own expectations for what students should know and be able to do at each grade level. These standards might reflect the tradition of local control of education, but they have made it difficult for students to move from state to state; students transferring from fourth grade in, say, Indiana, might face a different set of expectations when they arrive in fifth grade in Illinois. And, by fragmenting the educational marketplace, these varied standards have impeded the kinds of innovations that might otherwise come with economies of scale—in testing, textbooks, and teacher education.