You can contribute to the Anza Trail online interactive map
The National Park Service is usingMapCollaborator as a "web-based mapping tool and database for Anza Trail
Partners (agencies, non-profits, volunteers) to assist NPS in
documenting the Anza Recreational Trail and its resources. Once
approved by NPS staff, data entered on this site will be shared on our
public website at www.mapsportal.org/anzatrail." Here's a screen shot of a photo from Painted Rock Petroglyph Site along the trail, that pops up once the map site is clicked.