There are two streets in NYC that begin with X, if you don’t count Brooklyn’s Avenue X. Both are Xenia Streets: in Corona, Queens, and Old Town, Staten Island.
Xenia (which I had thought was a flower, but that’s zinnia) is a Greek term meaning ‘strange’ or ‘foreign’; it frequently turns up in combined terms like xenophobia, fear of strangers, or philoxenia, kindness toward strangers. It is also a city in Ohio and a variety of coral.
I don’t know how it ended up on two NYC street signs…