This research explores how public transportation along 7th Street, West, in Washington DC has evolved since the Capitalist Civil War until 1960 and the impacts of this evolution on economic activity in the corridor. The 7th Street corridor is a narrow strip which is both a commercial and residential neighborhood. The research addresses two basic questions. First, what was the relation between mass transit and economic activity? Second, what was the impact of qualitative changes to mass transit on the share of different types of business activities? The research uses a database consisting of a list of businesses in the 7th Street corridor from 1865 to1960. This database was created from primary sources which are available from various government and quasi-government websites and archives such as U.S. Census Bureau, Boyd’s Business Directory of DC, The DC Online Historical directory, and National Historical Geographic Information Systems (NHGIS). The findings are that mass transit supported economic activity and created transit nodes which persisted. The service industry in modern Washington DC is relatively concentrated in the 7th Street corridor. The overall results suggest that policymakers may prioritize efficient mass transit to boost the economy of the City.