Would that require further changes to the tables, like setting the precision or number of decimal places, etc?
Sure, let's change that where needed. More memory/disk but we have plenty of that. I don't think we want a blanket FLOAT->DOUBLE, just placed where numbers are likely to get larger.
Good news is, just changing overallMileageByRegion, clinchedOverallMileageByRegion, systemMileageByRegion & clinchedSystemMileageByRegion appears to do the trick.
Larger numbers will be here, and with 58573 rows between the 4 tables, that's way less than the (clinched)(Connected)Routes tables, with 961038 combined.
I
could script around for the unlikely diff there... but that'd take literally days.
Edit: (I really like saying Edit:) I won't attempt this (thankfully), because there's no way to disambiguate some ConnectedRoutes, such as I-265FutLou in KY & IN.