Solved Horizontal organization of blog archives pages

Our blog page correctly organizes the three column format in our grid horizontally, so that the most recent post is followed on its right by the second and third most recent. However, our blog archives pages for categories and tags for some reason organize blog posts by recency vertically, i.e., the second and third most recent posts are shown beneath the first post rather than to its right. I haven't been able to find tutorials that show how to fix this.
FYI, our general blog page: https://mklm.org/blog/
And an example of a category archives blog page: https://mklm.org/category/bolivia/
Tag archives page: https://mklm.org/category/bolivia/

Also the general blog page and the category archives nicely straighten out the rows, so each row is aligned at the top, whereas the tag archives pages don't.

Thanks for any help you can give.

 

Awesome, that worked. Thank you so much!