The urban centers of the United States have progressively started to use water more efficiently over the last several decades. But at the same time, rural America has gotten more wasteful, according to a new study in the journal Earth’s Future.

“As we are facing a more uncertain future regarding water resources, rural counties are being left behind.” Said Sankar Arumugam, the lead author of the paper, from North Carolina State University. “Rural counties appear to lack the resources, the political will, or both, to keep pace.”

The water-use efficiency was measured by per-capita consumption, and assessed in five-year increments from 1985 to 2010.

States like Washington and Pennsylvania showed improved efficiency consistently, over the entire period. But South Carolina, Oklahoma and Mississippi have gotten worse with each five-year segment.

The water waste was also tied to less education, and more poverty, they found.

Urban environments apparently improved their water use per person through efficiency technologies, and by retrofitting existing systems.

“There may be a role for huge infrastructure projects at some point, but these findings underscore the value of focusing on efficiency measures – and the need to pursue those measures in rural counties,” said Arumugam.

It is unclear whether agriculture in the rural areas could drive some of the increased per-capita consumption.

“Basic human needs” dictate between 15 and 25 gallons of water per day for a person, according to experts. But that amount is far exceeded by the average American, who uses 90 gallons daily.