A.
After the Civil War Abraham Lincoln was just the first of many US Presidents to encourage immigration through economic and politic measures (one of them was to give free land to anyone willing to work it). The country needed people to rebuild itself and to settle the west of the continent. And everyone was aware that there is plenty of space.
Answer:
I think it might be
Surrounding seas allowed people to set up ports for trade.
The location near the sea allowed people to interact with other civilizations.
A lack of flat land made people dependent on trade to survive.
Explanation:
Edit: dont listin to me im wrong im pretty sure
