Thanks for the kind words.

I am not an attorney, but that does not prevent me from excising my 1st amendment right to express an opinion. The PDF files that were produced by the USGS and which contain the hi-res scans are in the public domain.

Matt took that public domain data and did a pile of work to transform it into map tiles which programs like Gmap4 can display. In my view, Matt owns a copyright on his tiles. He is also paying out of his pocket to host them on Amazon so everyone can view them.

Keep in mind that all this is brand spanking new. Matt is still thinking through the details of how he is going to make these tiles available to others. I fully expect these tiles will show up in some phone apps and on other sites.

Bottom line - If you want to download the PDF files and do stuff with them, then you have already paid for them with your taxes. Goferit. But if you are thinking of doing a bunch of stuff with Matt's tiles, then I respectfully suggest you make a donation.