Which factor most contributed to the United States becoming a more multicultural society during the late 1700s and early 1800s?

The factor which most contributes to the United States becoming a more multicultural society was the immigration. Immigrants were generally welcomed in the late 1700s and early 1800s. Despite of the fear that immigrants would alter United States culture and customs, the match between Europeans seeking opportunity and an America in need of people left the immigration door wide open. Between 1783 and 1820, about 250,000 immigrants came to America. After 1820, ships captains had to report on the immigrants they brought to the United States, and since then 67 million immigrants have been admitted to the United States contributing to a multiplicity of cultural, social and ideological beliefs.