Final answer:
Prior to the 1930s, mass immigration to the U.S. primarily involved Southern and Eastern European countries such as Italy, Russia, and Austria-Hungary, while earlier immigration waves included many individuals from Germany and Ireland.
Step-by-step explanation:
Prior to the 1930s, the vast majority of immigrants to the United States came from southern and eastern Europe, with significant numbers arriving from Italy, Russia, and Austria-Hungary. These immigrants were often prompted by 'push' factors in their home countries, such as famines, religious and political persecution, or mandatory military service, and 'pulled' by the prospect of employment in the rapidly growing manufacturing industries of the Northeast and the Great Lakes area. Prior to this period, a major influx of immigrants also came from Germany and Ireland, starting in the 1820s, seeking economic opportunities and escaping from political unrest.
At the turn of the 20th century, immigrants from Europe accounted for more than 90% of the total number of immigrants to the U.S. However, this percentage significantly decreased by the end of the century. The pattern of immigration shifted over time, and by the 2000s, a larger proportion of immigration to the U.S. began coming from the rest of the Americas, especially Mexico, and various countries in Asia.