DSDR KB:

Metropolitan Statistical Areas (MSA) are one or more counties that contain a city of 50,000 or more, whereas Primary Metropolitan Statistical Areas (PMSA) are subareas that meet the qualification to be an MSA, but have a population of one million or more. PMSAs are always part of a Consolidated Metropolitan Statistical Area (CMSA).

Here is a link to the metropolitan areas at the time of the 2000 Census:

http://www.census.gov/population/estimates/metro-city/99mfips.txt

The Detroit-Ann Arbor-Flint CMSA (2162) is comprised of the Ann Arbor PMSA (0440), the Detroit PMSA (2160) and the Flint PMSA ( 2640).

Dothan, Alabama (2180) is an example of an MSA.

Note that the metropolitan area definitions have changed since the 2000 Census. The new definitions (November 2007) are:

http://www.census.gov/population/www/estimates/metro_general/2007/List4.txt

A good starting point is:

http://www.census.gov/population/www/estimates/metrodef.html

This link allows you to look at the definitions on selected dates for many different geographies. It will always include the latest standard.