Is there a way to create routes in MapSource, and export them to my Garmin GPSMAP 76CXs without totally re-generating all the map segments? I created a route and saved it to the micro SDHC card (using a reader/writer); the GPS unit doesn't see it at all. The spotty documentation seems to indicate that when you send directly from MapSource to the GPS, it totally overwrites the contents of the memory card. I'd appreciate any advice. I'd like to be able to navigate to a cache site.
When you send the route to the GPS, look at the dialog box in Transfer > Send To Device. Un-check everything but routes. That will insure that nothing is changed with your GPS'es map and waypoints. Only the route itself will be sent.
I had the experience that the Route file contained its own waypoints, and that downloading a Route replaced any previous routes, and that downloading waypoints replaced the previously downloaded set of waypoints.