  The nature of the spiral structure of the Milky Way has long been debated.
Only in the last decade have astronomers been able to accurately measure
distances to a substantial number of high-mass star-forming regions, the
classic tracers of spiral structure in galaxies. We report distance
measurements at radio wavelengths using the Very Long Baseline Array for eight
regions of massive star formation near the Local spiral arm of the Milky Way.
Combined with previous measurements, these observations reveal that the Local
Arm is larger than previously thought, and both its pitch angle and star
formation rate are comparable to those of the Galaxy's major spiral arms, such
as Sagittarius and Perseus. Toward the constellation Cygnus, sources in the
Local Arm extend for a great distance along our line of sight and roughly along
the solar orbit. Because of this orientation, these sources cluster both on the
sky and in velocity to form the complex and long enigmatic Cygnus X region. We
also identify a spur that branches between the Local and Sagittarius spiral
arms.
