I will mark branliest!

According to John Louis O'Sullivan, what is holding America back from its destiny?

"Manifest destiny" ... O'Sullivan argued that the United States had a divine mandate to expand throughout North America, writing of "our manifest destiny to overspread the continent allotted by Providence for the free development of our yearly multiplying millions."

Americans thought they were special because they thought that they were "chosen" by Providence to spread American ideals, and their population kept growing, so they needed to expand Westward.