a single room. If the new "propiska" of the new dweller violated this rule, the propiska would not be granted (spouses being an exception). This was officially meant to prevent unhealthy overcrowding of apartments and sexual abuse, but since most Soviet people had only a little over per person, it was also an effective method of migration control. These norms were very similar to getting onto the governmental (not dependent on particular employer) "housing list", which was yet another Soviet form of mortgage (again with real money replaced by years of working at one's workplace—the queue was free in terms of money). The main difference was that to gain admission to the housing list the space had to fall below the required per person in an existing apartment (and, due to the dwelling-area rule already mentioned, children of different gender also raised the chances of getting to the queue). This housing list was very slow (much slower than employers' list), and sometimes it took a person's whole life to get an apartment. As a result, practically the only way for a person legally to improve their living conditions was marriage or childbirth. This was also a serious driving force in migration of young people to "monocities", the new cities built from scratch, often in Siberia or the Arctic, some around a single facility (factory, oil region, or the like). Housing property rights and mortgage: pre/post Soviet In 1993, after the collapse of the Soviet Union in December 1991, propiska was restructured as resident registration, so the modern Russian legislation does not use the terms "propiska" and "propisat" (with the exception of situations where a reference is needed for the Soviet period). However, it is still used as a colloquial abbreviation for permanent residency registration. In the USSR, there had been some so-called "cooperative" apartments, owned on a Western-style mortgage basis, but they were scarce and getting one was very difficult. The three major post-Soviet reforms, to "not show ethnic background" on this still-vital document, private ownership (something previously disallowed), and seemingly free movement, being "able to register to live anywhere, once they arrange a written lease or buy a house" also ended the situation where these were the only apartments which passed down to children by inheritance. In normal apartments, when the last dweller died, the apartment was returned to the government: when the grandparents became older, they usually preferred