Final answer:
The Volga River flows through several cities in Russia and flows into the Caspian Sea. It is the longest river in Europe and plays a significant role in transportation and water resources in the region.
Step-by-step explanation:
The river that flows through Nizhny Novgorod, Kazan, Samara, Volgograd, and Astrakhan and flows to the Caspian Sea is the Volga River.
The Volga is the longest river in Europe and is an important transportation network in Russia, connecting major industrial centers and providing fresh water and fishing opportunities.