This paper develops an indicator that combines the area that residents can reach within a certain time of travel with population density to create a proxy for “accessibility”, i.e. access to employment and consumption opportunities. Using a large scale firm level dataset, with nearly one million firm year observations over 14 years, the paper quantifies the link between firm-level outcomes and the change in accessibility in Korea due to the expansion of the network of major roads. The results suggest that the most productive firms benefited in terms of employment, output, and productivity, as accessibility improved. For the majority of incumbent firms, improved accessibility leaves most balance sheet variables broadly unaffected, but is associated with a decrease in fixed assets. The estimates also suggest that there was little job displacement, with the exception of service sectors where employment increased in response to improved local accessibility and declined for long distance accessibility.