Since the DISCONNECTED_ROUTE datacheck was put into place a while ago, most have been addressed but several continue to linger. Most are in the northwestern US but a few are scattered elsewhere. I know these often have the complication that the common border point to use needs to be agreed upon by the maintainers of the regions where the routes (should) meet, but they're also very easy to fix once that agreement is made.
So I'm requesting that everyone with remaining DISCONNECTED_ROUTE errors involving any of your regions try to make this a priority in your TM contributions in the near future.
(Of course, all datacheck errors in active systems should be addressed promptly or marked as FPs, so please fix them all while you're in!)