This could be the most detailed open-data map of urban gerontology in existence; the Portland project used about half of the number of property records. It’s not a flawless diamond, though. Some of the dates are approximate or inaccurate.
Most copyright disputes involve some question of whether creators should be compensated for their work, thereby fostering more of it. But this one is unusual in running up against the fundamental right to ownership of the laws you have to obey. The court will have a tricky job in balancing the two.