Redirect blog urls from root to /blog

I searched around and couldn’t find an answer to this situation.

Previously, a site I’m running loaded blogs in this way:

domain.com/blog-url-of-post

Over the past year, I don’t remember exactly when, that was changed to:

domain.com/blog/blog-url-of-post

Despite the sitemap updating I’ve found that when looking through analytics and searching for posts via search engines the results are:

domain.com/blog-url-of-post

Obviously that’s not a good because there is nothing there.

The idea of redirecting every blog via .htaccess is overwhelming and so I thought I’d ask the community if there was a better idea/suggestion. I’d create blog.domain.com but I don’t see that resolving the issue for all the search results or links that may be on other sites, etc.

Any thoughts?