The shape of this district resembles an inverted triangle with its long base on the north along the Pima-Pinal county border and its narrow part on the south, generally running along the northern boundary of Tucson. The northwestern corner of the district is at the point where I-10 crosses into Pima County. From there, the boundary follows I-10 south to a point approximately where the freeway intersects the Rillito River. From there, the district line jogs west to pick up the development on the west side of the freeway and goes south to Sweetwater Dr., where it comes back east to the highway. It again follows I-10 south to Prince Rd. and then east to approximately Fairview Ave., where it begins a zig-zag course north and east to the Rillito River at First Ave. It then follows the river east to Craycroft Rd., north on Craycroft to Sunrise Dr. and west for a mile to Swan Rd. The line follows Swan north to Skyline Dr. and then west again for a mile to Alvernon Way, where it intersects the border of the Catalina Mountains section of the Coronado National Forest. It follows the national forest boundary to approximately Bear Canyon. It then runs along various ridgelines and drainages in the Catalina Mountains, past the summit at Mt. Lemmon and down the north side of the mountains to the Pinal County line. The district line follows the county border west to I-10 except for a peninsula into Pinal County to include SaddleBrooke, Catalina and Biosphere2.