We measure the Galactic rotation curve and its first two vertical derivatives in the first and fourth quadrants of the Milky Way using the 21 cm VGPS and SGPS .
We find tangent velocities of the atomic gas as a function of galactic longitude and latitude by fitting an analytic line profile to the edges of the velocity profiles .
The shape of the analytic profile depends only on the tangent velocity and the velocity dispersion of the gas .
We use two complementary methods to analyze the tangent velocities : a global model to fit typical parameter values and a local fitting routine to examine spatial variations .
We confirm the validity of our fitting routines by testing simple models .
Both the global and local fits are consistent with a vertical falloff in the rotation curve of - 22 \pm 6 km s ^ { -1 } kpc ^ { -1 } within 100 pc of the Galactic midplane .
The magnitude of the falloff is several times larger than what would be expected from the change in the potential alone , indicating some other physical process is important .
The falloff we measure is consistent in magnitude with that measured in the halo gas of other galaxies .