The placement patterns of most U.S. law schools are closely tied to their regional labor market. In our 2006 ranking article, Andy Morriss and I documented the close relationship between geographic proximity and the number of large firms who participate in a school's OCI program. More recently, I posted some interesting data suggesting that the presence of a regional law school (or schools) in a metropolitan area can depress the income of solo and small firm lawyers.
To help capture these patterns, I have just posted new metropolitan area codes on the HM Rankings website, which link together Census Bureau FIPS codes for place, county, CBSA (Core Based Statistical Area), and CSA (Consolidated Statistical Area), to the 2008 ABA Official Guide dataset. These files are in both SPSS and STATA format. They can be added to the base dataset using a simple join command.
For an overview of the CBSA and CSA coding system, which became the primary standard in 2003, see the documents posted at this link.