My Maps in Google Drive

Custom maps created in Google My Maps are now saved in Google Drive. You can also create custom maps from Google Drive by clicking the "New" button, then picking "More" and "Google My Maps".

"Over the next week, all the maps you've created will also be accessible in Google Drive, so you can easily organize, manage and share them," informs Google. For now, I've only been able to find new maps, not the maps created before the Drive integration.