The existing contract covering the teachers expired on January 18. Negotiations between the Denver Public Schools District and the Denver Classroom Teachers Association had carried on for 15 months without an agreement. The union, which represents most of the district's 5,600 teachers, is seeking a total package of $28.5 million; the district was seeking a total package of $23.3 million. The two sides also had competing versions of how to apportion whatever figure is eventually agreed on: teachers were seeking more chances to get a pay increase, whereas the district wants to put teachers in high-poverty schools as a way of getting a bonus, as part of a pay-for-performance program on which both sides once agreed, a system that was instituted in 2006 and held up as a national model. Teachers now say that the bonuses vary too much from year to year and that the district has not made transparent how it measures performance.

District officials said that all 161 schools in the district would be open while the strike is on, and substitute teachers will be available in some cases; classes at early childhood education centers will not take place. The district now has 90,000 students.

Teachers who go on strike will not receive unemployment benefits. Technically, the district can declare striking teachers to be in neglect of duty and have them dismissed; such an action would almost certainly face a legal challenge, experts have said.

The last strike in the Denver school district was 25 years ago. Teachers across Colorado walked out in large numbers for a time in 2018, but that was not a general strike.

• Teachers in Arizona won some concessions after a six-day walkout.
• Kentucky lawmakers overrode the governor's veto of spending bills providing more funds for teachers.
• Teachers in Oklahoma won some concessions but ended a nine-day strike without gaining more.