A day that once had walls

This being St. Patrick's Day, it's a good time to remind ourselves it's also a day when some noisemakers want to build walls.

The Irish of more than a century ago encountered the same walls in America, a traditional enterprise over the years that would exclude blacks, Jews,  Catholics, Italians, Muslims, Germans, Japanese, Asians and Middle Easterners, depending on the prevailing prejudicial winds.  Which one is in your family tree?