Final answer:
Americans of European descent most often trace their ancestry to Germany and Ireland.
Step-by-step explanation:
From the information provided, Americans of European descent most often trace their ancestry to Germany and Ireland. In fact, the majority of Americans were of German ethnicity by the end of the 19th century. Today, 46 million Americans are of German descent, making it the largest ethnic group in the country. Following Germany, the top five ethnicities for Americans of European descent are Black or African American, Mexican, Irish, and English.