United States
On January 2, 1974, President Richard Nixon signed the Emergency Highway Energy Conservation Act, creating a national maximum speed limit of 55 mph. The policy responded to the 1973 oil crisis by aiming to reduce fuel consumption on American highways. Supporters argued it conserved energy and improved safety outcomes. Critics contended it interfered with state authority and did not reflect regional driving conditions. Over time, Congress modified and then repealed the national limit, returning speed decisions to the states in the 1990s. The episode illustrated how energy shocks can drive nationwide transportation policy.