This research project examines the partition of India as a natural experiment and the impact of changes in market access. For this analysis, we utilize population censuses in 20th century in British India for pre-partition and India, Pakistan and Bangladesh for post-partition. From the theoretical predictions of New Economic Geography, border regions are expected to suffer substantial decline due to a decrease in market access. This research aims to test this prediction. Through the study of historical economic division, which is the opposite of economic integration, we intend to contribute to the understanding of future economic integration in South Asia.