In 2018, there were 20 major work stoppages involving 485,000 workers, the highest since 2007, per new Bureau of Labor Statistics data. Education strikes overwhelmingly dominated, and they show no sign of stopping in 2019.

The big picture: Strikes by educators have been a tipping point in the unrest over wages and other needs. A Chicago Teachers Union strike from 2012, which was the largest that year with 185,500 lost worker days, wouldn't even make the top three in 2018.

Driving the news: Oakland teachers went on strike Thursday, joining Los Angeles and Denver among major U.S. cities that have seen teachers' strikes in recent months.

Strikes that challenged state governments in 2018:

Arizona: 486,000 lost worker days Oklahoma: 405,000 lost worker days West Virginia: 319,000 lost worker days Colorado: 126,000 lost worker days North Carolina: 123,000 lost worker days Kentucky: 52,000 lost worker days

“There is no strike wave. People are not strike happy. Marches of teachers are realizing they can do something when the powers that be won’t listen to their needs."

— Randi Weingarten, president, American Federation of Teachers

What to watch: Weingarten said the unrest will keep bubbling over.

West Virginia had its second walkout in less than a year where teachers are protesting a bill that would open 7 charter schools.

The first Denver teacher strike in 25 years ended last Thursday while union and district negotiators are in compensation talks, CNN reports.

Teachers in Los Angeles, the country's second-biggest school district, went on strike in January for the first time in 30 years. California also had teachers from three charter schools strike in January, a first for the state.

Summit Academy Parma teachers in Ohio are on strike strike, citing wage discrepancies.

Striking Chicago International Charter School teachers resumed classes Tuesday after a tentative deal included pay increases, class-size limits and scheduling changes.

Methodology: BLS tracks work stoppages of more than 1,000 lost worker days and counts work days and non-holidays only.

Go deeper: Teachers quit at highest rate on record in 2018