In just 40 years, americans dealt with:
a civil war
millions of freed slaves
industrial revolution
millions of new immigrants
changes in education
women's suffrage movements
indian wars
burgeoning city populations
technological advances

The U.S. was forced to deal with profound changes in a relatively short period of time. For example, in just forty years, Americans dealt with:

a civil war

millions of freed slaves

industrial revolution

millions of new immigrants

changes in education

women's suffrage movements

Native American wars

burgeoning city populations

technological advances

so basically all of the above,

Including burgeoning city populations.

i hope this helps someone :)

answer-the island had airfields that the u.s. military needed.

the answer is "focused on"

lol gave an answer 1 week that's the answer for those who need it in the future xd