ASJA/The American Society of Journalists and Authors is a professional association of independent nonfiction writers (since 1948). There is a nonrefundable $50 application fee plus an initiation fee of $50. On top of that, you’ll pay annual dues of $210. “ASJA membership requires evidence of a sustained professional career–that you have written, on a freelance basis, full-length bylined articles in major publications over a substantial period of time, or have had nonfiction books published by established publishers, or other equivalent freelance activity” described on the website.
Here’s a web page with links to many more writers’ organizations including the Authors Coalition of America, National Writers Union, PEN America, and more.
Algonquin Hotdish is a monthly social gathering of writers and other creative professionals in the Minneapolis-St. Paul, Minnesota area. Contact Kit Naylor at firstname.lastname@example.org for details.
SMA Literary Sala (San Miguel de Allende, Guanajuato, Mexico)
LinkedIn groups (most require application for membership):