In that period, immigration laws became more sever, meaning that people could not enter the country easily or immigrate. There were even laws that declared that specific ethnic groups cannot enter, such as the immigration laws that banned the Chinese people from entering, or the Gentleman's agreement with Japan that did not forbid Japanese people from coming, but enabled Japan to prevent people from sending their people. Things like literacy and history tests were introduced to prevent people from entering if they weren't similar to the US people.
