Where has all the Cyrillic gone?

One last thought on Latvia. I wasn’t there for long, but in all that time I saw 1 (one) sign in Cyrillic, a modern sign on some sort of educational institution next to the hotel. Given that the USSR annexed the country for 50 years from 1939, and Latvia had been under Russian imperial control from 1720 to 1918, I was amazed that there weren’t any inscriptions, old signs or public pieces of writing in Russian, particularly since (as mentioned in an earlier post) Latvian is still a minority first language in Rīga. There was one in German – which must have dated from before 1700 – but nothing in Russian. I wonder how prevalent Russian was pre-1991, and how quickly the language moved over to Latvian primacy. I remember reading that there was a controversial law mandating Latvian-language signage a few years back, but as far as I’m aware that didn’t mandate the removal of Russian signs.