A section of U.S. 191 south of Willcox reopened Wednesday after more than a week of work to repair major cracks from soil erosion.
The highway was closed July 5 between Birch Road at milepost 53.1 and Dragoon Road at milepost 55.7.
The Arizona Department of Transportation is consulting with geotechnical experts to determine the cause of the ground erosion, officials said in a news release Wednesday. Crews will also monitor the highway for additional cracking.
A possible cause, several experts and advocates told the Arizona Daily Star last week, is unregulated groundwater pumping in rural areas. Excessive groundwater pumping can cause fissuring when the removal of large amounts of water from an aquifer causes the land holding that water to sink, a process caused subsidence.
The repair work involved removing pavement to expose cracks, which were then filled with a concrete slurry mix, and a layer of asphalt was applied on a section of the highway, ADOT said.
The agency is asking drivers to use extra caution until lane stripes are applied to the new pavement.
