Quite a lot of the gpx “route” files on this site are recorded tracks rather than actual “Routes” – as these have a much larger number of points and so are more acurate as they are recorded by a GPS unit “in the field”.
Most GPS programs have some sort of function to convert routes to tracks and tracks to routes. I’ve not used MapSource but i’m sure it will have such a function. Have a look in the help files and FAQs for your software. Otherwise you might want to use a different bit of software – theres plenty of good free ones available.