I found a good article written by Laura about Ellis Island on the footnote blog. I did not realize that Ellis Island didn't open until January 1st 1892. There is so much information available for those ancestors that came through Ellis Island. Unfortunately, none of mine did. Laura writes that twelve million immigrants did arrive via Ellis Island over the course of six decades. Was yours one of them?
Consider other ports of entry. I found a few on the east coast.
Bath, Maine, 1825 - 1867
Belfast, Maine, 1820 - 1851
We think of the United States as 1776 forward. What if your ancestors were here before that? One that I researched was William Dyer. He arrived in the new world in June 1629 at the port of Boston.