Valerie Bauerlein:

North Carolina is a right-to-work state, and teachers typically must request permission to take a personal day off for this type of action, and be willing to cover the cost of hiring a substitute. The state’s big school boards canceled classes after more teachers requested personal time off than there were substitutes available.

Keith Poston, executive director of the Public School Forum of North Carolina, which isn’t affiliated with the march but advocates increased state spending, said he sees the rally as teachers reacting to a decade of declining overall spending, from fewer school nurses and teaching assistants to less money for supplies and professional development.

“They have a front-row seat for the disinvestment in public education,” Mr. Poston said. “Our elected officials, whatever party they’re in, should listen to what they’re saying.”

The one-day rally is expected to tie up traffic in downtown Raleigh for most of the day, as teachers and other protesters travel from the North Carolina Association of Educators headquarters to the General Assembly on its opening legislative day.

Terry Stoops, a former public-school teacher who researches education for Raleigh’s libertarian-leaning John Locke Foundation, said the North Carolina rally is different from those in other states because it is unlikely to change public policy.

“People will harden their positions,” Mr. Stoops said. “The real motive here is to replace the Republican majority in the General Assembly.”