In 1898 the parish of St Albans absorbed St Michael Urban, St Peter Urban and Sandridge Urban so the parish and borough occupied the same area. In 1901 the population of the borough was 16,019, growing to 18,133 in 1911. St Albans expanded in 1913 by gaining parts of Sandridge Rural (241 acres), St Michael Rural (138 acres), St Peter Rural (992 acres) and St Stephen (335 acres). In 1921 the population of the enlarged borough was 25,593, growing to 28,624 in 1931. It expanded again in 1935 as part of a county review order gaining more of St Michael Rural (890 acres), St Peter Rural (436 acres) and St Stephen (712 acres). The population of the borough was 44,098 in 1951 and 50,293 in 1961.