Grand Canyon National Park Backcountry Planning links:
Compiled in October of 2019 to create single no-internet-needed resource for quick Grand Canyon planning that I could easily share and put on my computer/phone/tablet... This resource will not stay up to date - but should be very useful offline/compiled info for a number of years. The links below should stay more up-to-date.
All the details straight from the NPS including the dates when you can submit permits. I find this page, with its plethora of processes/forms/rules, appropriately discouraging about the availability of permits... However it is worth noting that - especially for lightly used areas (see the usage information below) and with some flexibility - it is possible to walk up to the Backcountry Office Window and get a permit for the next day but, of course, it is also possible that nothing works out!
Needed for backcountry permits and not found on all trail maps.
I am not sure if this table is/stays completely current but it offers more information than the list on the official Backcountry Page.
A useful visualization of popular and less used areas - the information is not up-to-date but is still useful. This information is from the documents included with the proposed Backcountry Management Plan on the NPS Planning, Environment and Public Comment site