It appears that I have been getting comprise wrong as I have been using "is comprised of". My dictionary (Chambers) defines it as "v.t. to contain or to include" and saying "the US is contained of... would certainly grate".

I checked that little program, Guru Net, that someone recommended in a Mudcat thread. Here is what it had to say on the usage:

USAGE NOTE: The traditional rule states that the whole comprises the parts; the parts compose the whole. In strict usage: The Union comprises 50 states. Fifty states compose (or constitute or make up) the Union. While this distinction is still maintained by many writers, comprise is increasingly used, especially in the passive, in place of compose: The Union is comprised of 50 states. In an earlier survey, a majority of the Usage Panel found this use of comprise unacceptable.

Jon