  We suggest a revised distance to the supernova remnant (SNR) G109.1-1.0 (CTB
109) and its associated anomalous X-ray pulsar (AXP) 1E 2259+586 by analyzing
21cm HI-line and 12CO-line spectra of CTB 109, HII region Sh 152, and the
adjacent molecular cloud complex. CTB 109 has been established to be
interacting with a large molecular cloud (recession velocity at v=-55 km s^-1).
The highest radial velocities of absorption features towards CTB 109 (-56 km
s^-1) and Sh 152 (-65 km s^-1) are larger than the recombination line velocity
(-50 km s^-1) of Sh 152 demonstrating the velocity reversal within the Perseus
arm. The molecular cloud has cold HI column density large enough to produce HI
self-absorption (HISA) and HI narrow self-absorption (HINSA) if it was at the
near side of the velocity reversal. Absence of both HISA and HINSA indicates
that the cloud is at the far side of the velocity reversal within the Perseus
Arm, so we obtain a distance for CTB 109 of 4+/-0.8 kpc. The new distance still
leads to a normal explosion energy for CTB 109/AXP 1E 2259+586.
