A lack of regional data on the occupational structure in England and Wales during the interwar years has so far prevented extensive study of this time period. In the current paper, we fill this gap by reconstructing the occupational structure at the district level, based on a recently-digitized register for 1939 and by linking this dataset with the population censuses of 1911 and 1921. The resulting data reveals significant regional differences in the expansion of the tertiary sector, and the relative decline of agricultural and industrial activities. For industry, we find an increase in the level of geographical concentration during 1911–1921, to decline by 1939. The primary sector followed a similar pattern, whereas activities in the tertiary sector became less concentrated.