The first attempts to create a transcontinental railroad failed in part because the technology was not sufficient. Congress could not agree on where the line would run. the Civil War blocked construction.

relations between the soviet union and the united states were driven by a complex interplay of ideological, political, and economic factors, which led to shifts between cautious cooperation and often bitter superpower rivalry over the years. the distinct differences in the political systems of the two countries often prevented them from reaching a mutual understanding on key policy issues and even, as in the case of the cuban missile crisis, brought them to the brink of war.

the united states government was initially hostile to the soviet leaders for taking russia out of world war i and was opposed to a state ideologically based on communism. although the united states embarked on a famine relief program in the soviet union in the early 1920s and american businessmen established commercial ties there during the period of the new economic policy (1921–29), the two countries did not establish diplomatic relations until 1933. by that time, the totalitarian nature of joseph stalin's regime presented an insurmountable obstacle to friendly relations with the west. although world war ii brought the two countries into alliance, based on the common aim of defeating nazi germany, the soviet union's aggressive, antidemocratic policy toward eastern europe had created tensions even before the war ended.

evaluate the extent to which the seven years' war (french and indian war, 1754–1763) marked a turning point in american relations with great britain, analyzing what changed and what stayed the same from the period before the war to the period after it.

president johnson announced to the american people during his television address on march 31, 1968 that he had ordered a partial bombing halt over north vietnam.