This settlement grew up around a railway junction, and is these days primarily known as a place where you have to change trains. The railway station is oversized for the town's own needs. Hallsberg was declared a municipalsamhälle (a type of borough within its municipality) in 1883 and got the title of a market town (köping) in 1908. Since 1971 it is instead the seat of the enlarged Hallsberg Municipality.
A sight in the Hallsberg is the Bergööska House, built in the 1880s. It was drawn by the architect Ferdinand Boberg, and contains wall-paintings by Carl Larsson, depicting the Bergöö family and other well-known people of Hallsberg.
The main industries are Volvo, Ahlsell, and enterprises related to the railway industry.