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As part of the BeSSeL Survey, we report trigonometric parallaxes and propermotions of molecular maser sources associated with 13 distant high mass starforming regions in the Sagittarius spiral arm of the Milky Way. In particular,we obtain improved parallax distance estimates for three well studied regions:1.9 +0.1/-0.1 kpc for M17, 5.3 +1.3/-0.9 kpc for W51, and 7.9 +0.9/-0.7 kpc forGAL 045.5+00.0. Peculiar motions for all but one source are less than 20 km/s.We fit a log-periodic spiral to the locations and estimate an average pitchangle of 7.2+-1.9 deg. We find that the section of the arm beyond the tangentpoint in the first quadrant of the Milky Way appears 15 pc below theIAU-defined Galactic plane.

Trigonometric Parallaxes of Star Forming Regions Beyond the Tangent Point of the Sagittarius Spiral Arm