DENVER (KDVR) — More U.S. school districts are adopting a four-day week, including in Colorado.

In more than 13,000 school districts nationwide, nearly 900 operate on a truncated schedule. That’s up from 100 in 1999 and 662 in 2019.

The figures are according to Paul Thompson, an associate professor of economics at Oregon State University, who tracks and researches shortened school weeks.

Thompson counted four-day school weeks in 25 states during the 2022-23 school year. Compared to the 2018-19 school year, his research showed more four-day school weeks around the country, including in Colorado.

More districts adopt 4-day school weeks

Thompson counted 105 Colorado school districts with four-day weeks during the 2018-19 school year. That increased to 120 by last school year — some 67% of Colorado’s 178 school districts.

Colorado previously led the U.S. in its number of school districts with four-day weeks. But as of last year’s count, Missouri has more on the shortened schedule — some 150 of them, and nearly five times as many as a few years prior.

Texas also saw a big shift to the four-day week last school year, going from one to 66 districts.

Colorado’s 4-day school weeks allowed since 1980

Hundreds of school systems around the country have adopted four-day weeks in recent years, mostly in rural and western parts of the U.S. Districts cite cost savings and advantages for teacher recruitment, although some have questioned the effects on students who already missed out on significant learning during the pandemic.

Some turn to a shortened schedule to save money. An analysis by the Economic Commission of the States found such savings were modest, totaling 0.4% to 2.5% of their annual budgets.

The Colorado legislature first allowed alternative schedules in 1980, with 12 districts approved for the switch by 1981. That number had nearly tripled at the start of the 1990s.

As of August, some 128 Colorado school districts and others with charter or alternative operations were on a reduced academic calendar. But not all use the four-day school week, according to the Colorado Department of Education.

Most of Colorado’s 178 school districts are small and rural — 110 of them have fewer than 1,000 total students.

The Associated Press contributed to this report.