 It had a population of around 125 in January 2017

Aalsum is built on a partially excavated terp, around a church originally dedicated to St. Catherine of Alexandria, which dates back to approximately 1200 AD.Aalsum had a station ("Dokkum-Aalsum") on the North Friesland Railway, which opened in 1901.It became the terminus for passenger services in May 1935 and closed to passengers in July 1936.