What 19th century construction projects provided the greatest boom to economic unification in both the u. s. and canada?
a. the building of massive dams and hydroelectric projects
b. the building of telephone and telegraph systems
c. the building of transcontinental railroads
d. the building of highways and bridges

i believe the answer would be 1.

in 1803 the louisiana purchase took place, doubling the size of the country. by 1840 almost 7 million americans had migrated westward in hopes of securing land and being prosperous. the belief that settlers were destined to expand to the west is often referred to as manifest destiny.

explanation: