Child 44 is defined by the tension between the urban and rural regions of Russia. Urban Moscow may be under the firm control of Soviet authorities, but the rural countryside refuses to let go of traditional Russian culture.
Think of it this way: while the big cities in Russia are built up under the assumption that man can do great things in the future—as is the Soviet government—the countryside is notably resistant to change and attached to traditions. While both viewpoints have their place, it's the latter that proves most valuable to Leo during his investigation.
The Concrete Jungle
Moscow is the heart of the Soviet Union. The city is large and industrialized, filled with a sizable population—and a more sizable police presence. This is embodied by the Lubyanka, the MGB's interrogation facility–"there was something about the building itself which made people uneasy, as though fear had been factored into the design" (2.7.1). Citizens are terrified of being brought within those walls: the result is generally death or the Gulag.
This creates an unmistakable climate of fear. You can't trust anyone: not your neighbors, not your friends, and definitely not your family. Anyone could be an MGB agent in disguise, and anyone could go off to the MGB and tattle on you, often for no reason at all. This is exemplified in Raisa's school: students are desperate to prove their love for the State, "none [...] wanting to seem less dedicated than their neighbor" (2.10.4). Everyone has to wear a mask all the time, shielding their true feelings and beliefs even from their loved ones.
After growing up in this environment, Leo is shocked by life in rural Russia. Despite the rise of the U.S.S.R, the old Russia is alive and well—there are still "communities built around bucket wells and ancient myths" dotting the countryside (2.6.17). No matter how hard the government tries to ideologically purge the country, it's going to take a lot to tear up a culture with such deep roots.
Leo's exile leads him to Voualsk, a town that straddles the line between these two archetypes. Though Voualsk had been a small village for most of its history, it was thrust into prominence after the government built an automobile factory in the area. Voualsk is still far from being a major urban center like Moscow—the classrooms are certainly more relaxed—but we can see the beginning of the transformation ahead.