When Arizona was first divided into congressional districts as a result of the 1950 Census, the 1st District comprised all of Maricopa County, home to Phoenix, while the rest of the state was in the 2nd District. In a mid-decade redistricting resulting from Wesberry v. Sanders in 1967, the 1st was cut back to eastern Phoenix and most of what became the East Valley.
Over the years, the 1st's share of Phoenix was gradually reduced due to the area's explosive growth in the second half of the 20th century. However, it remained based in the East Valley until Arizona picked up two seats in the 2000 U.S. Census. The old 1st essentially became the 6th District, while a new 1st District was created to serve most of the state outside of Phoenix and Tucson.
After the 2012 redistricting, the Hopi reservation was drawn into the 1st District; it had previously been included within the 2nd District. Also included were some northern suburbs of Tucson that had been in the 8th, as well as a tiny section of Phoenix itself near the Gila River Indian Community. Meanwhile, heavily Republican Prescott, the old 1st's largest city, and much of surrounding Yavapai County were drawn into the new, heavily Republican 4th District. The district is now considered to be significantly more competitive for Democrats.
This large congressional district covers the mainly rural areas of northern and eastern Arizona. Democrats perform well in Flagstaff, Sedona, and the Navajo Nation among Native Americans, while Republicans are strongest in the more rural white areas. Elections are usually decided by conservative "Pinto Democrats" throughout the rural areas. Due to its vast size, it is extremely difficult to campaign in and has few unifying influences.
George W. Bush received 54% of the vote in this district in 2004. John McCain also carried the district in 2008 with 54.4% of the vote while Barack Obama received 44.3%. In the 2012 presidential election Mitt Romney (R) won with 50% of the vote, with Obama receiving 48%. Due to intense competition, this is generally considered a swing district. The redistricting has increased the number of historically Democratic voters.