 During the 19th Century Germans were the second-largest immigrant group to the United States, behind only the ethnic Irish.The wave of German immigration began slowly, averaging about 20,000 people per year during the decades of the 1830s and early 1840s, before exploding after the economic crisis of 1847 and the failure of the Revolution of 1848 in the German states.when the first wave of mass emigration peaked, 1854, some 220,000 Germans lifted up stakes in the fatherland for a new home in America.