  We find the lower central series for residually nilpotent Baumslag-Solitar
groups, and find the intersection of all terms of the lower central series.
Also, we find non-abelian Bauslag-Solitar groups for which the lower central
series has length 2. For some Baumslag-Solitar groups a connection is found
between the intersection of all subgroups of finite index and the intersection
of all terms of the lower central series.
