USPop data frame has 22 rows and 1 columns.
This is a decennial time-series, from 1790 to 2000.
This data frame contains the following columns:
Population in millions.
U.S.~Census Bureau: http://www.census-charts.com/Population/pop-us-1790-2000.html, downloaded 1 May 2008.
Fox, J. (2008) Applied Regression Analysis and Generalized Linear Models, Second Edition. Sage.