Kites are an interesting aspect of this. It's a bit of a trope, in some media, that ninjas can use man-sized kites for sneaking into places or for spying. Although the documented history of this is thin. Apparently Marco Polo reported that in China, sailors would send a man up on a kite to scout!

In the US, it is different for each state. In Indiana, the estate goes to probate and distant relatives will be tracked down. In rare cases where there are none to be found, it will go to the state.