The problem of census undercounts, a familiar political issue for modern groups or instrumentalities that consider themselves underrepresented in the Census Bureau statistics, has only recently attracted attention from historians. While the modern “miss rate” is potentially high among some groups (the reason for the emphasis on the homeless in the 1990 census), the general rate of underenumeration appears to have diminished in recent censuses. The bureau acknowledges a net undercount of 5.6% of the population in 1940; the error declined gradually to an estimated 1.4% in 1980 (Burnham 1986; Anderson 1988; Edmondson 1988).

Nineteenth-century censuses no doubt contained more serious errors. Although he did not have underenumeration specifically in mind, the administrator for the 1870 census said that “the censuses of 1850, 1860, and of 1870 are loaded with bad statistics. There are statistics in the census of 1870,I am sorry to say, where some of the results are false to the extent of one-half. They had to be published then, because the law called for it; but I took the liberty of branding them as untrustworthy and in some cases giving the reasons therefore at some length” (quoted in Sharpless and Shortridge 1975: 411). Strikingly modern quarrels surrounded the accuracy of the 1840 Boston and New Orleans censuses, while the errors in the 1870 enumeration of New York City and Philadelphia were sufficient to cause recounts of both cities (ibid. ; Knights 1971: 145).