This paper analyzes the impact of the German autobahn net on the economic performance of German regions. To address endogeneity and reverse causation problems, we use historical instrument variables, i.e. a plan of the railroad net in 1890 and a plan of the autobahn net in 1937. We find a statistically and economically significant causal effect of transport infrastructure investments as measured by changes in the length of the autobahn net of West German NUTS 3 areas on regional employment and the wage bill.