The history of Caslan began in 1914, when the Alberta and Great Waterways Railway Company (A&GWR) established a railway station there during a period of aggressive rail expansion in northern Alberta. Following the arrival of the railway, homesteaders and pioneers began trickling into the wooded region. Local historical records note that the first recorded baby in the area was born in 1921, marking the literal establishment of a permanent family-based community.

The Post Office opened March 21, 1933. The first postmaster was Alexander Gordon, who held the position untl 1946.