In his 1962 Foreign Language Units of Kansas: Atlas and Statistics, Justice Neale Carman determined a so-called “critical year” for every non-English speaking group settlement in Kansas. The “critical year” was the approximate date by which time only about half of the families with children in a given community were still using the immigrant language or dialect regularly in the home.
Carman allows for a two-to-five year period on either side of this date. Thus, for a particular community, if he assigns the date of 1930 as the "critical year" it should be interpreted as within two years or possibly as many as five years before or after that date. This means there is a high probability that the "critical year" was reached between 1928 and 1932, but it could have been as early as 1925 or as late as 1935. Despite the limitations of Carman’s estimate, the "critical year" provides us with an approximate idea of the state of linguistic assimilation of a speech community to the dominant English society.Updated January 18, 2010