Possible travel restrictions in 1920's?
I am trying to understand if there may have been some sort of travel restriction to explain why my Great Grandfather would not be allowed to leave Russia to be with his wife and children in Latvia in 1924. They were all living in Russia for 2-3 years and were in St Petersburg at the time my Great Grandmother and her two children left to avoid starvation. Apparently they had to apply to leave/go back to Latvia a couple of times before being accepted, but my Great Grandfather stayed in St Petersburg. I understand there was a lot of political unrest/issues at that time, but I can't find anything about travel restrictions within the Soviet Union. My great Grandfather lived most of his life in Riga, so I would have to believe he would have some right to go back with his family. Does anyone have any ideas?