Parents in Wyoming spend less money on back to school shopping than any other state, according to a new Promo Codes survey which estimates the average family in the Cowboy State spends $100 per student, less than half the national average of $207.30 per child.

Along with Wyoming, North Dakota ($112), New Mexico ($123), Montana ($137), and Oklahoma ($147) were the only states where back-to-school clothing and supplies averaged under $150 per student.

Washington, D.C. is the most expensive area for back-to-school shopping with the average family spending $325 per child, followed by Arkansas ($299), Minnesota ($270), Colorado ($257), and Missouri ($253).

Several other states around the region topped the national average for back-to-school expenses, including Idaho ($247), Utah ($230), Nebraska ($223), and South Dakota ($211).

The survey cites clothing as the biggest expense for parents, followed by pens, pencils, and notebooks. High School juniors are the most expensive grade ($272) with seventh graders ($262) and 10th graders ($248) close behind. Third grade was the only grade in the survey with average back-to-school expenses under $200.