Locations and forms of spiral arm segments in the Milky Way as determined from trigonometric parallaxes of water and methanol masers (Reid et al. 2014, and references therein) associated with HMSFRs (solid lines). Dashed lines indicate extrapolations based on fits of log-periodic spiral forms to the parallax data. Arm segments are labeled as follows: Outer (Out), Perseus (Per), Local (Loc), Carina near portion (CrN), Sagittarius near and far portions (SgN, SgF), Scutum near and far portions (ScN, ScF), Norma or 4 kpc (Nor), 3 kpc near and far arms (3kN, 3kF), and Connecting (Con). Also shown are other features including the Aquila Rift (AqR), Aquila Spur (AqS), and the Local spur (LoS). The Outer Scutum–Centaurus (OSC), Carina far (CrF), an exension of Connecting (CnX), and Centaurus-Crux near and far (CtN and CtF) arm segements currently have no parallax measurements and are not plotted. The Galactic Center and Sun are indicated with a red asterisk and red Sun symbol.