The emergence of quantitative history as a distinct approach dates to the 1960s, when the convergence of at least three trends prompted historians to turn to numeric data and statistical analysis for help in answering questions and framing interpretations.

First was a growing interest in the experiences of ordinary people as distinct from the achievements of "great white men." Political historians, for example, had long focused on the thoughts and actions of presidents, prominent congressmen, and other "movers and shakers" in the national government. But modern polling techniques suggested that voters did not always share the values and views of the public officials they voted for. Leaders could not automatically be considered spokespeople for their followers. So how was a historian to find out what really motivated ordinary people to vote for one person or one party rather than another? In an effort to answer that question, a group of "new political historians" turned to the study of voting behavior, using electoral data and increasingly complicated statistical techniques to determine which factors best explained voting patterns in particular areas during given periods of time. Likewise, "new social historians" set out to study history from "the bottom up." One question they wanted to address was whether the American ideal of equal opportunity was historical fact or fiction. Had it really been possible for poor yet meritorious Americans to rise to positions of wealth and status, or was the American social structure more bounded by hereditary constraints than implied by the "myth of the self-made man" and "the American dream"? Using census records, tax lists, and other quantifiable material, the new social historians sought to determine the extent of social mobility in American history. They found that dramatic improvements in social position were rare, but modest changes were more common.

A second trend that contributed to the rise of quantitative history was the movement to establish history as a social science dedicated to the rigorous, consistent, and precise application of social theory and social scientific methods in the study of past human behavior. Thus the new political historians of the 1960s borrowed from political science, and the new social historians borrowed from sociology. Yet the most celebrated and most controversial proponents of social-scientific approaches were the "new economic historians," who applied highly mathematical econometric theory and methodology to the study of longstanding historical questions and often came up with unorthodox answers. One famous example (at least within academic circles) will suffice. Conventional wisdom held that the key explanation for the acceleration of American economic growth during the nineteenth century was the advent and expansion of railroads. Robert Fogel decided to test this hypothesis by constructing a "counterfactual" model of what the nineteenth-century American economy would have looked like without railroads. He imagined a network of canals rather than railroads and then, building on limited data and a body of theoretical assumptions, he calculated the probable rate of economic growth under these alternative circumstances. To his avowed surprise, he concluded that canals would have served the economy almost as well as railroads, and hence that railroads were not indispensable to American economic growth in the nineteenth century. Not everybody was convinced, but few could ignore Fogel’s audacious approach. He was later awarded the Nobel Prize in Economics in large part because of this pioneering work in the new economic history.

The third factor that encouraged the rise of quantitative history in the United States and elsewhere was the advent of the digital computer. In the early 1960s, huge mainframe computers cost hundreds of thousands of dollars each. The first academic "power users" tended to be natural scientists, but over time social scientists also discovered the advantage of these huge electronic devices for processing large amounts of information and executing elaborate calculations involving many variables and complex manipulation of the data. By comparison to many of their colleagues in related disciplines, historians were rather late in making the transition from note cards to punch cards, the essential input media of the mainframe era. As late as 1965, only a few dozen historians were involved in computerized research projects nationwide. But by the early 1970s, the computer revolution was reaching into history graduate programs, and increasing numbers of young historians learned the basic procedures of data entry and analysis using software such as SPSS. Especially for the study of large populations with hundreds of "data elements," the mainframe computer proved a godsend. Still, most historians continued to shy away from computers until the triumph of the personal computer in the 1980s and the advent of user-friendly software for word processing as well as statistical manipulation. Today the typical personal computer sitting on a faculty desk or in a college computer lab is hundreds of times more powerful and also much easier to use than the enormously expensive mainframes of the founding era of quantitative history.