Why was the Mexican Cession a significant event?

It united different cultural groups living in western areas

It intensified the debate over the expansion of slavery

It created a temporary southern border

Il led to the development of canal systems to move goods

It intensified the debate over the expansion of slavery. This event was significant because it added vast territories to the United States, raising questions about whether slavery would be allowed in these new areas. The debate over the extension of slavery ultimately played a major role in leading to the American Civil War.