I too lived, (I was of old Brooklyn,) I too walked the streets of Manhattan Island, and bathed in the waters around it, I too felt the curious abrupt questionings stir within me, In the day, among crowds of people, sometimes they came upon me, In my walks home late at night, or as I lay in my bed, they came upon me.
Here again we get that classic Whitman phrase, "I too."
Just like us (not really), Whitman lived in Brooklyn, walked around Manhattan, and bathed in the East River, which could couldn't do today – it's much too polluted.
And there's that word "curious" again. Doesn't "curious abrupt questionings," sound a little sexual? With Whitman it's always hard to tell, because he does a good job of covering his tracks. He could be talking about his earlier "curiosity" about the other passengers on his ship, although this, too, was never described in detail.
At any rate, he has these questionings at night in bed, too.