Myers on the Supreme Court's singular vs plural use of 'United States'

Supreme Court Usage and the Making of an 'Is' has just been posted by Minor Myers, Brooklyn Law School. It appeared in Green Bag 2D (2008). Here's the abstract:

This survey examines use of the phrases “United States is” and “United States are” in opinions of the United States Supreme Court from 1790 to 1919. The familiar claim, popularized by Shelby Foote in the Ken Burns Civil War documentary, is that the Civil War marked a shift in usage from plural to singular. This survey demonstrates that in the Supreme Court this account of the timing of the change is not accurate. Although patterns of usage changed abruptly in the 1860s, justices continued to use the plural form through the end of the nineteenth century. Indeed, the plural usage was the predominant usage in the 1870s, 1880s, and 1890s. Only in the beginning of the twentieth century did the singular usage achieve preeminence and the plural usage disappear almost entirely.