There are a lot of mapping resources online and some can be fairly complex to use.

Grinding gravel

Developing a route for a mixed terrain ride can be challenging. Recently, Strava moved a lot of their mapping tools behind a pay wall. I have found that Gaia GPS is a good replacement, although, most notably, it does not have a heatmap overlay.

Finding interesting roads and trails can be challenging. Gravelmap depends on users to upload activities. In contrast, Seeking Dirt uses goverment GIS data on road surface information, but unfortunately, currently does not include Maine.

OpenStreetMap includes a surface tag, which can be queried and then displayed using overpass turbo.

[bbox:{{bbox}}];
( 
    nwr["surface"="unpaved"];
    nwr["surface"="gravel"];
    nwr["surface"="ground"];
    nwr["surface"="dirt"];
    nwr["railway"="abandoned"];
    nwr["snowmobile"="yes"];
);
out body;
>;
out skel qt;

Mapping sites designed for mountain biking like Trailforks can also be helpful in defining routes.

Sanford and Eastern Railroad

Resources

Parcels

Trails