Teacher protests in Arizona and Colorado are the latest in the US, where cuts to education budgets strain schools.

Teachers in the US states of Arizona and Colorado left their classrooms on Thursday to call for better pay and increases in public school funding.

Tens of thousands of educators marched through the streets of Phoenix, the capital of Arizona, demanding that legislators fix a number of issues, including low educator salaries and overcrowded classrooms with more than 30 students per teacher.

In an April 19 poll by the Arizona Education Association (AEA) and grassroots organising group Arizona Educators United, 78 percent of 57,000 educators voted in support of the walkout. It is the first in the state’s history.

Meanwhile, teachers in Colorado also protested on Thursday, resulting in the closure of several school districts, according to local media.

Schools across the United States have seen their budgets slashed since the economic downturn of 2007, known as the Great Recession.

The protests in Arizona and Colorado follow similar demonstrations in West Virginia, Oklahoma and Kentucky.

Decreased budgets not only lowered teacher salaries but also cut funding for school programmes and supplies. Teachers have been known to work multiple jobs and pay for teaching supplies out of their own pockets.

Educators decided on the Arizona walkout after state Governor Doug Ducey proposed a plan to raise their salaries 20 percent by 2020.

Those protesting said the proposed plan did not offer enough improvements fast enough, and that they want the state government to implement annual improvements to bring Arizona education spending in line with national averages.

AEA president Joe Thomas told reporters on Thursday he doesn’t expect an early end to the walkout.

Teachers in Colorado will hold another “Day of Action” on Friday, including a march to the Capitol and displaying their graded papers to demonstrate how “much work educators do outside of the school day,” according to the Colorado Education Association.

In Colorado, legislators from both parties have agreed to give schools the largest budget increase since the Great Recession, but teachers say it isn’t enough.

They also see a clear source of education funding: The taxes earned from the legalisation of cannabis.

Colorado legalised the recreational use of cannabis in 2012. The move was a boon to Colorado’s tax income.

In 2014, the first year both medical and recreational cannabis were legally available, sales reached $700m.

The 2012 bill committed to delivering millions of tax dollars to the state’s public education budget, though educators say it has not been enough. Colorado schools say they need $18bn to cover costs through 2018.