1956
1,578 miles covered
{The trailblazer:} Missouri’s I-70 (aka Mark Twain Highway) is the first interstate to be fully constructed with funding from the Federal Highway Act.
1957
4,914 miles covered
1958
6,112 miles covered
1959
7,581 miles covered
1960
8,226 miles covered
1961
8,346 miles covered
1962
10,633 miles covered
1963
12,328 miles covered
1964
12,662 miles covered
1965
13,595 miles covered
1966
15,415 miles covered
{Pedal to the metal:} Averaging roughly four miles per day, the U.S. adds over 15,000 miles to the Interstate Highway System within the first ten years.
1967
16,133 miles covered
1968
20,633 miles covered
1969
22,557 miles covered
1970
23,525 miles covered
1971
25,308 miles covered
1972
27,172 miles covered
1973
27,943 miles covered
1974
28,940 miles covered
1975
30,416 miles covered
1976
33,464 miles covered
1977
34,295 miles covered
1978
35,304 miles covered
1979
36,499 miles covered
{Border to border:} The completion of I-5 in California links Canada and Mexico with one seamless route.
1980
37,964 miles covered
1981
38,538 miles covered
1982
39,304 miles covered
1983
39,504 miles covered
1984
39,955 miles covered
1985
40,494 miles covered
1986
41,186 miles covered
{Connecting the coasts:} Final sections of I-80 open to traffic, making it the first coast-to-coast highway.
1987
42,385 miles covered
1988
42,834 miles covered
1989
42,887 miles covered
1990
43,949 miles covered
1991
44,163 miles covered
1992
44,828 miles covered
{Mission I-70 accomplished:} 36 years after the first section was constructed in Missouri, I-70 opens in Colorado as it was originally envisioned in the Federal-Aid Highway Act of 1944.
1993
44,863 miles covered
1994
44,888 miles covered
1995
45,434 miles covered
1996
45,767 miles covered
1997
46,146 miles covered
1998
46,146 miles covered
1999
46,193 miles covered
2000
46,193 miles covered
2001
46,193 miles covered
2002
46,205 miles covered
2003
46,263 miles covered
2004
46,271 miles covered
2005
46,271 miles covered
2006
46,279 miles covered
2007
46,510 miles covered
2008
46,603 miles covered
2009
46,603 miles covered
2010
46,603 miles covered
2011
46,680 miles covered
2012
47,106 miles covered
2013
47,237 miles covered
2014
47,252 miles covered
2015
47,616 miles covered
2016
47,711 miles covered
2017
47,783 miles covered
2018
47,814 miles covered
{Over 60 years later (and counting):} Totalling over 47,000 miles, the Interstate Highway System accounts for 25% of all highway traffic in the United States.
