I'm also frustrated by the lack of sourcing here but the wiki article for downtown [1] also points to Manhattan, citing a book I don't have a copy of. Allegedly

I'm also frustrated by the lack of sourcing here but the wiki article for downtown [1] also points to Manhattan, citing a book I don't have a copy of. Allegedly it was in use in Manhattan in the 1830s, which aligns with the date given by the etymology entry linked previously. [1] https://en.m.wikipedia.org/wiki/Downtown https://en.m.wikipedia.org/wiki/Downtown