Soviet Russia kept undesirables (criminals and political dissidents) away from view by banning them from coming closer than 101km to major urban centres.
Many countries have a phrase that means something like “beyond cultured civilisation” – beyond the pale, beyond the black stump, the boondocks, the sticks, the wops, et cetera. In Russia, you would talk about someone being past the 101st kilometre, and it persists today despite being a relic of Soviet oppression.
The Soviet Union wanted to keep ex-criminals out of sight and out of trouble. Political dissent was criminalized, of course, so it was desirable for the government to keep the potential agitators away from large groups of people. Their approach was a kind of internal Soviet exile. Ex-cons were not allowed to settle within 101km of any major metropolitan area: Moscow, Kiev, Minsk, Sevastopol, and so on.
Foreigners visiting the Soviet Union had the reverse – they were not allowed to travel further than 25km away from city centres. So I suppose there was always a buffer of 76km between the two. These rules also created a sharply divided country: areas of prosperity in the urban areas, and an impoverished countryside beyond the 101st km. The law no longer exists, but it continues to echo in people’s perceptions.