CASPER, Wyo. (AP) — U.S. Census Bureau data shows the populations of Casper, Worland, Rock Springs and many other Wyoming cities and towns decreased last year.

The Casper Star-Tribune reports that Casper saw the biggest drop in sheer numbers, losing 351 people. Thermopolis had the largest drop as a proportion of its population, losing 3 % of its residents.

It's part of a trend that included about three-quarters of Wyoming's larger cities and towns, census estimates show.

Cheyenne's population grew by more than any other city of town in Wyoming, gaining 370 new residents, or a little over 1%.

Wyoming has the smallest population in the U.S., and it began to shrink after the 2015 energy bust brought downturns in the coal, oil and natural gas sectors.