After the American Civil War and the subsequent abolition of slavery in the 1860s, the Reconstruction Amendments to the United States Constitution granted emancipation and constitutional rights of citizenship to all African Americans, most of whom had recently been enslaved.
Answer: Roads
Explanation:
All roads lead to Rome, and the Incas had roads to communicate as well, and likewise, the Aztecs built canals and Roads to unite their empire.
The main reason would be the environment because of the fact their population is so big, they need enough room for everyone. There's also the connection with having available food source within the environment when the people plan to settle in. There's also the idea of desirable climate which helps them with food sources and allows them to flourish instead of dying off.