What's with that whataboutism? I don't care about the US. Why do your type brings it up every time, like it makes USSR's wrongdoings more acceptable. It doesn't. It's rather a lesson to learn and not repeat in your country.

and the USSR had a tendency to send a massive amount of their prisoners to Siberia, which would make it difficult to help build apartment blocks several thousand miles away.

So? They built infrastructure there, yes, so it's enormous territory can be somehow crossable. And they also built infrastructure, housing and plants\factories all over it's territory. Gulag wasn't just a one small camp, it's the Main Office of Camp (Managenent), it had a lot of people to send elsewhere, based on what Kremlin wants.