Run MARC commuter trains into Virginia. It could draw thousands more riders

The Washington region has two commuter rail systems funneling riders from Maryland and Virginia into the District. But currently, those systems — MARC in Maryland and VRE in Virginia — both terminate at Union Station, and don’t continue into the other state. The notion of integrating MARC and VRE into a “through-running” system has been a perennial area of interest amongst transit advocates and officials in the region.