In the 1850's a political party was born in the United States called the "American Party". The foundation platforms for this new party were anti-Catholic, xenophobic, and hostilty to immigration.
When asked by outsiders what the party stood for the common response was "I know nothing" which resulted in the party being renamed the "Know Nothing" party. Because of the wide net of conspiracy regarding a shadow government being ran from the Vatican the party didn't grow very quickly and in fact in the South the anti-Catholic vision was struck from the party altogether.
In the vacuum of opposition to the Democrat Party a new party was born in the mid 1850's, the Republican Party. This party was born out of opposition to "the slave power" but they needed to reach out to the Know Nothings to further establish their base. The Republican party rose to power with the election of Abraham Lincoln and the Know Nothing party was dissolved. Yet, their vision, their call of a common fear of outsiders, and conspiracy theories is woven in the Republican party DNA today.
In 2016 we see the takeover of a political party by one man who has appealed to the worse characteristics of what is to be an American. When our call to make America great means we leave a swath of people on the outside of this vision then we have failed to demonstrate the love of liberty and justice that birthed this great nation in the first place. Though there will always be a tension between the current population and the immigrants wishing to also make their home here it doesn't have to be an all-or-nothing proposition. When fear dictates our policy rather than faith in the goodness of our people and values then we have truly lost our way as a nation.