Which factor contributed most to the cultural diversity in Canada and US?

The most significant factor contributing to cultural diversity in Canada and the United States is Immigration. Both countries have long histories of welcoming immigrants from various parts of the world, bringing with them distinct languages, traditions, and customs. This influx has fostered multicultural societies, where different cultural groups coexist and interact. Additionally, indigenous populations and historical colonization also play important roles in shaping the cultural landscape of both nations.