According to Albert Barnes, their mistake was that they didn't speak against slavery. Although many of them believed that slavery was against god and against the idea that god made everyone equal, they didn't do much against it out of many reasons, either they thought it was a necessary evil or they were afraid of the public reaction.
It depends on the context. During the Industrialization era of the United States, hundreds of thousands of immigrants from Germany, Ireland, Italy, and other European countries came to the United States in hopes of finding a better life. Many of these immigrants stayed in cities (the Irish in particular) and were seen to factory managers as incredibly useful and cheap labor, as they do not know how the American life was. These immigrants were taken advantage of and worked long hours with very little wage. Politicians, too, saw immigrants as easy votes. Others were not as thrilled to the new influx of immigrants. Many American citizens were threatened by the increasing population of European immigrants and felt like they were taking away jobs and land from "native" Americans (not to be confused with the indigenous peoples that inhabited the United States territory prior to the Age of Exploration). They developed the concept of nativism, which was the argument that because immigrants were never born or raised in the United States, they should not have as much as an opportunity as those who were born and raised in the country. This concept of thinking still exists today. Hope this helps!
It was known that there was an economic boom taking place just after the second world war. It could be due to effective economic policies implemented by various governments. Such policies include the reduction of the tax rates, and economies were regulated so as to avoid excessive spending.
