Month Millions Of Miles 1920-01-01 17.8500 1920-02-01 16.1500 1920-03-01 17.9700 1920-04-01 17.1200 1920-05-01 18.1300 1920-06-01 18.4600 1920-07-01 19.9500 1920-08-01 19.8100 1920-09-01 19.1600 1920-10-01 17.4900 1920-11-01 17.5900 1920-12-01 18.2600 1921-01-01 18.2700 1921-02-01 16.7700 1921-03-01 18.4600 1921-04-01 14.6900 1921-05-01 10.4800 1921-06-01 10.7300 1921-07-01 17.7500 1921-08-01 20.5700 1921-09-01 19.6100 1921-10-01 19.0600 1921-11-01 18.6500 1921-12-01 19.2300 1922-01-01 18.8800 1922-02-01 17.4100 1922-03-01 19.5300 1922-04-01 18.0700 1922-05-01 19.9200 1922-06-01 20.2100 1922-07-01 21.5700 1922-08-01 22.4400 1922-09-01 21.3000 1922-10-01 20.0000 1922-11-01 19.6400 1922-12-01 19.3900 1923-01-01 20.3400 1923-02-01 18.2200 1923-03-01 20.1000 1923-04-01 19.3800 1923-05-01 21.0600 1923-06-01 20.9000 1923-07-01 22.7100 1923-08-01 23.8900 1923-09-01 21.9000 1923-10-01 21.4300 1923-11-01 20.4900 1923-12-01 20.2500 1924-01-01 17.9200 1924-02-01 19.6900 1924-03-01 20.6700 1924-04-01 20.4000 1924-05-01 21.7400 1924-06-01 21.4200 1924-07-01 23.9400 1924-08-01 24.0500 1924-09-01 22.6200 1924-10-01 21.5600 1924-11-01 19.8300 1924-12-01 20.6200 1925-01-01 21.1900 1925-02-01 18.9900 1925-03-01 20.7900 1925-04-01 20.5700 1925-05-01 21.4400 1925-06-01 22.3600 1925-07-01 24.5900 1925-08-01 24.8200 1925-09-01 23.1300 1925-10-01 22.0600 1925-11-01 20.3700 1925-12-01 21.3000 1926-01-01 21.1300 1926-02-01 19.3900 1926-03-01 21.7800 1926-04-01 20.9900 1926-05-01 9.92000 1926-06-01 13.8000 1926-07-01 19.3600 1926-08-01 22.7100 1926-09-01 21.9000 1926-10-01 21.4200 1926-11-01 20.1700 1926-12-01 20.9300 1927-01-01 21.1100 1927-02-01 19.3400 1927-03-01 21.9000 1927-04-01 21.2400 1927-05-01 21.8500 1927-06-01 23.0400 1927-07-01 24.8900 1927-08-01 25.6400 1927-09-01 23.7900 1927-10-01 22.1000 1927-11-01 21.4900 1927-12-01 22.2400 1928-01-01 21.7700 1928-02-01 20.7700 1928-03-01 22.5400 1928-04-01 21.2900 1928-05-01 23.4400 1928-06-01 23.6000 1928-07-01 25.5400 1928-08-01 26.7400 1928-09-01 24.0000 1928-10-01 23.2100 1928-11-01 22.0500 1928-12-01 21.9600 1929-01-01 22.8500 1929-02-01 20.4200 1929-03-01 22.3400 1929-04-01 22.6200 1929-05-01 24.1300 1929-06-01 23.6100 1929-07-01 26.6700 1929-08-01 27.4300 1929-09-01 24.3200 1929-10-01 23.7300 1929-11-01 22.5200 1929-12-01 22.3800 1930-01-01 23.3400 1930-02-01 20.8700 1930-03-01 22.8700 1930-04-01 22.7800 1930-05-01 23.8700 1930-06-01 24.1700 1930-07-01 26.8100 1930-08-01 27.0500 1930-09-01 24.7300 1930-10-01 23.5800 1930-11-01 21.8900 1930-12-01 22.6000 1931-01-01 23.1100 1931-02-01 20.6700 1931-03-01 22.6500 1931-04-01 22.4600 1931-05-01 23.5700 1931-06-01 23.9300 1931-07-01 26.0800 1931-08-01 26.5200 1931-09-01 24.0500 1931-10-01 23.3100 1931-11-01 21.6100 1931-12-01 22.5500