Q. Federal Register Online
The Federal Register is the official daily publication for rules, proposed rules, and notices of Federal agencies and organizations, as well as executive orders and other presidential documents.
You can search or browse past issues of the Federal Register online for the years 1994-present on the US GPO web site: http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR
Individual US DOT operating administrations also post proposed and final rules on their web sites: http://www.dot.gov/administrations
Federal Register issues from before 1994 are available in print and microform, and via commercial vendors such as LexisNexis and Westlaw back to around 1980.
You can also check the "Current CFR Parts Affected" site at http://www.gpo.gov/fdsys/browse/collectionCfrFR.action?collectionCode=CFRPARTS for a list of the parts of title 49 that have been changed during the current year (or month or day).