In 2013 there were almost 317 million people living in the United States, or slightly less than 5 per cent of the world's population.
In 1700, more than two centuries after Columbus's voyage of discovery, the population of the continental United States was approximately 1 million, or 0.17 per cent of the world total.
By 1914 it had risen to almost 100 million (already 5.5 per cent of the world total), as a result of both a high rate of natural increase and mass immigration — over 20 million in the century beginning in 1820. Some of this was involuntary, although the 399,000 slaves imported from Africa were much less important than natural increase in the slave population (which had reached 4.5 million by 1860) and were dwarfed by the almost 9 million slaves transported to the rest of the Americas. The total US population continued to grow at least twice as fast as that of Western Europe, with a further net migration of more than 31 million between 1913 and 1998 (see Maddison, 2006 for details). At the start of the new millennium, 10.4 per cent of the population was foreign-born, up from a low of 4.8 per cent in 1970 but still well below the peak of 14.7 per cent in 1910. Three in every four Americans now lived in urban areas (Hughes and Cain, 2011, 358).Rapid population growth was accompanied by even faster expansion in output, which grew at annual rates of almost 4 per cent in the periods 1820—1913 and 1950—73, and almost 3 per cent in both 1913—50 and 1973—98. In consequence the United States' share of world GDP rose from a miniscule 0.1 per cent in 1700 to a peak of 27.3 per cent in 1950; in 2001 it still accounted for 21.4 per cent of world output. In terms of GDP per capita, the US had moved from fifth place in 1820, when it lagged behind Belgium, the Netherlands, the UK and Switzerland and was barely ahead of the Western European average, to lead the world in 1950, with output per head more than double that of Western Europe. By 1998 the gap had closed a little, but the US still had a 35 per cent advantage over the second richest nation (Japan) and a slightly more than 50 per cent lead over Western Europe (again see Maddison, 2006).
This remarkable growth in output was not entirely smooth or continuous, being interrupted by cyclical downturns of variable length and severity (the most dramatic being the Great Depression of the 1930s), and the benefits were very unevenly distributed between rich and poor. It was made possible by the profound structural changes that transformed a predominantly agricultural economy into the world's greatest industrial power (responsible for half the world's manufacturing output in 1945) and then into its most advanced post-industrial nation. The primary sector (agriculture, forestry and fishing) still employed 37.5 per cent of the working population in 1910; by 1950 this had fallen to 11.9 per cent, and by 2007 to a mere 0.7 per cent. The share of secondary employment (manufacturing, construction and transport) peaked at 41.0 per cent in 1950 and more than halved over the next half century, falling to 22.6 per cent in 2007 (Hughes and Cain, 2011, 567). By this time the tertiary (service) sector accounted for 76.8 per cent of total employment, and the largest US enterprises (in terms of stock market valuation) were no longer steel companies or car manufacturers but Information Technology corporations like Microsoft and Google.
There were equally profound social changes. In 1500 the Native American inhabitants were predominantly nomadic hunter-gatherers, although there was a significant settled agricultural population in some areas. By 1861 the native inhabitants had been almost completely displaced by European settlers, who were themselves divided between three quite distinct (though closely connected) modes of production: capitalism, simple commodity production (mainly by independent farmers) and slavery. In contrast with Europe, there was of course no landowning feudal aristocracy. In the next half century, with slavery abolished in 1865 at the end of the Civil War and the frontier now closed, the US had become an overwhelmingly capitalist country, in which the great majority of the population were legally free but had no alternative means of subsistence other than the sale of their labour power in waged employment.
From about 1890 there was a rapid expansion of large corporations with substantial market power, initiating what is sometimes described as the ‘monopoly stage' of US capitalism, which on some accounts has persisted until the present day.The very distinctive economic and social development of the US is reflected in the prevailing ideology, which combined ‘the idea — derived from initial Puritan settlement — of a nation enjoying divine favour, imbued with a sacred calling; and the belief — derived from the War of Independence — that a republic endowed with a constitution of liberty for all times had arisen in the New World'. The result was ‘a complexio oppositorum of exceptionalism and universalism. The United States was unique among nations, yet at the same time a lode-star for the world: an order at once historically unexampled and ultimately compelling example to all' (Anderson, 2013, 6).
This pervasive American exceptionalism has exercised an extremely important influence on the development of the social sciences, including economics (Ross, 1991). It has induced a long-standing and persistent hostility to all forms of socialism, and has also encouraged resistance to government intervention in the economy. For this reason the US is sometimes seen as the leading example of a ‘Liberal Market Economy', in contrast to the ‘Co-ordinated Market Economies' of Northern and North-Western Europe. Certainly the US has always had a significantly smaller government sector, as can be seen from the ratio of government expenditure to GDP, which in 1913 was 8.0 per cent, compared with a 12.0 per cent average in four European countries (France, Germany, Netherlands, UK). By 1999 it had risen to 30.1 per cent, but the four-country European average was now 45.9 per cent (Maddison, 2006, 135).