The first modern population census was con- ducted on October 1, 1925 during the Japanese colonial era. Thereafter, Japanese authorities con- ducted a census every ve years for a total of ve censuses through 1944. Between 1925 and 1944, Korea’s population increased by six million, from approximately 19 million to 25 million. All re- gions gained population during the period. The Hamgyeong-do and Pyeongan-do regions gained

one million each, which accounted for 33% of the total population increase. This is related to the Japanese strategy of establishing various industri- al facilities in Korea’s northern provinces to serve as advanced logistics bases to invade China. The population increase rates of the central and north- ern provinces were also higher than the national average.