Sorry! It was a bug due to redirecting from / to /businesses. Therefore clicking the back button would take you to / again, which would automatically redirect to /businesses. I just fixed it by using replaceState. I hadn't tested this before, because I just launched the site and therefore hadn't previously linked to it -- I'd always visited directly.
As a quick tip, I don't think any modern browsers allow a site to wipe out history from previously visited sites. In this case for example two quick hits to the back button should have worked.
You can click and hold the back button to move backward more than one history instance.
