In order to design a new power‐transmission tower built with a cantilevered and tapered thin‐walled steel member instead of the usual angle steel or pipe, the governing equations for a doubly symmetric and linearly tapered thin‐walled member are presented in a general way by means of Hamilton's principle. Closed‐form solutions are indicated for the static problems. Next, the exactness of the proposed elastic solutions is proven using numerical calculations for a cantilevered and linearly tapered thin‐walled member with a circular, octagonal, or rectangular transverse cross section. It is shown that the mechanical behavior of the cantilevered and linearly tapered thin‐walled members is remarkably different from that of the cantilevered thin‐walled member with uniform cross section and that the difference arises even for fairly small tapering angles. The effect of the transverse shear deformation for the current problem is shown to be negligible.