"Peter" wrote in message ...
snip

http://www.epa.gov/otaq/invntory/envspoms.txt :
"The 55 mph national speed limit was introduced January 1,
1974 in response to the OPEC oil embargo and subsequent "energy
crisis." While this speed limit was not mandated by the Federal
Government, highway funding was linked to adoption of this
speed limit, and its enforcement, by the States."


Just like the DWI and exhaust emissions laws...