In what ways did the issue of slavery make westward expansion more complicated?

Western expansion was impacted by slavery because as the new states were admitted to the Union it could affect the balance of power on the slavery issue, whether they were either pro or anti-slavery.

Explanation:

Westward expansion was complicated for the United States because of the issue of slavery. The slave states in the Southern United States were worried that admitting more states to the Union would affect the balance of power they had in government that would protect their interests. Before the civil war, the northern cities in the Eastern United States grew to be major industrial metropolises which tended to rely on immigrant labor. The South however required the slave system to assure a cheap labor supply for agricultural work on the plantations.  When the United States threatened to expand westward slaveholding became more divisive because non-slaveholding white settlers did not want to compete with slaveholders who had cheaper sources of labor. This is one of the tensions that led to the civil war.

the factors that the economies of the muslim empires prosper were:

1- land trade routes-located between three continents  

2- sea trade routes

trade contributed to the spread of muslim empires, and with that islamic culture led to a growing feeling of internationalism resulted in the transfer of technology, science, and other cultural forms.