The state's estimate of ground rents: about 115,000.

The number of ground-rent registrations processed as of Wednesday morning: about 70,000.

Ground rents still to be processed because they were brought in or mailed right before the deadline: No one knows how many yet -- but the assessment office was so flooded by last-minute applicants that it had to reassign some staffers to help out.

Any ground rents that weren't in assessors' hands or postmarked by Wednesday officially cease to exist, and the owners can no longer collect. (A lawsuit is challenging that rule, so the future of unregistered ground rents could change.)

Some ground rents, of course, have ceased to exist since the state's 2007 estimate for another reason -- the owner of the home bought it in order to also own the land.

Wondering if there's ground rent on a particular property? It could take several months for all the applications to be processed, but as they are, the state is linking the applications to the property look-up page. Type in the address you're interested in and see if there's a "ground rent registration" link near the top right corner.