Marion Stokes recorded 40,000+ tapes of news from Philadelphia starting in the early '70s using U-Matic and B&W formats. Internet Archive has been working hard to digitize her collection.
This is the reason why I go to estate sales, have put thousands of miles on my car doing so, and have picked up eBay lots and Goodwill Outlet bin tapes. Because if not, they go to the landfill. NEVER to be seen again. Just like the original tapes of Johnny Carson in his NYC days, or Doctor Who. All wiped out because no one bothered to save them in the pre-digital days. Local news? Stations never kept those either! So whenever I find a 1991 late newscast from a small market, it is very likely that I have the only copy in existence.
I have copies of parades and festivals that aired on local television. No guarantee that master tapes exist.
I thank Michael Pannoni in MD, Scott in Ohio, Chandler in NC, etc. for continuing this crusade to save television history, too. While we know that shows like As the World Turns have full archives somewhere at CBS (or in a vault at the Procter & Gamble headquarters), these local newscasts, local sports broadcasts, and other events likely have no master source anymore.
Rick at Obsolete Video Series deserves immense praise, too. His EIAJ, U-Matic, and 1" conversions have resulted in 1960s-1970s television being saved... EVEN A FEW JOHNNY CARSON SHOWS FROM NEW YORK! Donate to him when you have a chance!!