A series of laws known collectively as the Alien and Sedition Acts were passed by the Federalist Congress in 1798 and signed into law by President Adams. These laws included new powers to deport foreigners as well as making it harder for new immigrants to vote.
They were afraid of large numbers of Jews coming in from (in the case of the St. Louis) Germany. 900 people is a lot of people but it would only be the tip of the iceberg if people were allowed to cross the Atlantic and go into the United States. There was a quota of how many people could come in and the US wanted to keep to the quota system.
The United States (at the time of the St. Louis sailing) was neutral, so they also didn't want to endanger that neutrality.
The differences are that Magna Carta<span> was made to set rules and give rights to the nobility, royalty, and other high-ranking officials of that time, and the </span>Constitution<span> was written to give rules and rights to all people.</span>
