In 1974, the United States instituted a national speed limit of 55 miles per hour (mph), a move that

generated a great deal of controversy. Proponents of the lower speed limit managed to avoid repeal

of this national speed limit by effectively arguing that driving at 55 mph significantly reduced the

number of traffic fatalities on U.S. Highways. The argument was based on the fact that the total

number of traffic fatalities dropped from 55,511 in 1973 to only 46,402 in 1974. Because people

have questioned the validity of this argument, you are going to examine more rigorously the

hypothesis that the reduction in fatalities was due to the institution of the 55 mph speed limit.

Procedure.

Since the change to a 55 mph speed limit occurred a number of years ago, you must use archival

data in your study. The U.S. Government routinely makes available a wide variety of data on the U.

S. Population. Most public and private libraries either own or would be able to get the national or

state statistics you need. Here is the data you would obtain for the present research question:

1966=53,041

1967=52,924

1968=55,200

1969=55,791

1970=54,633

1971=52,660

1972=56,278

1973=55,511

1974=46,402

1975=45,853

1976=47,038

1977=49,510

1978=50,226