create blog posts under specific directory

Looks like you’re running WordPress at the server root (https://www.mainsite.com/). That means you’d need to add the “blog” part of the URL manually.

To do that, you could modify the Permalink structure to include “blog” at the directory root.

On your WordPress Dashboard, go to Settings > Permalinks

Then, under Common Settings, choose Custom Structure. Add “blog” behind /%postname%/, so it looks like this:

https://www.mainsite.com/blog/%postname%/

Would this set all of my pages to be part of this sub directory as well? I figured that would be the answer, but I dont want to make the change and screw up the existing pages.

Existing setup:
https://www.mainsite.com/page1

I do not want this to happen:
https://www.mainsite.com/blog/page1 (NOT OK)

https://www.mainsite.com/blog/post1 (OK)

The Permalinks setting will only affect your blog Posts, not your Pages, so you’re safe.

https://www.mainsite.com/page1 will not show up as https://www.mainsite.com/blog/page1

Excellent, Thank you Adam! This is exactly what I was looking for.