More Notable Events on March 6: 1990 SR-71 sets a transcontinental record, flying 2,404 miles in 1:08:17 1981 Walter Cronkite signs-off as anchorman of CBS Evening News 1964 Constantine succeeds Paul I as king of Greece 1940 1st U.S. telecast from an airplane, New York City 1836 3,000 Mexicans beat 182 Texans at the Alamo, after 13 day fight