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.
The short answer here is that he first became the totalitarian ruler and then used his authority to make a totalitarian state. He was voted Chancellor in 1933 but he used his power to make the Reichstag pass the Enabling Act which allowed him to pass the laws without the participation of the Reichstag and thus taking the complete control of the state. He achieved this through persuasion and violence.
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