The Peace and Justice Action League, organizers of the march in Spokane, also is protesting the Trump administration's proposed budget, an outline of how Americans' tax dollars could be spent in 2018.
Liz Moore, director of the Action League, says cuts to departments overseeing education, social services, environmental protections and more would be devastating. She also says the corresponding $54-billion increase in military spending is misguided.
"A budget is a moral document and is about the values of the community it represents - or the country in this case - and the Trump budget does not reflect our values," she said. "So we are marching to reject the Trump budget."
Trump is the first president to refuse to release his tax returns to the public in 40 years. He says he won't release his returns while they're being audited.
While the biggest march is expected to be in Washington, D.C., local marches are scheduled across Washington, including in Anacortes, Richland and Olympia. The Spokane march begins downtown at noon.
Moore says the Women's March in January was one of the largest protests in Spokane's history. She says since then, the heat has been on members of Congress representing Washington to oppose Trump administration policies.
However, she says both Washington's U.S. senators, Patty Murray and Maria Cantwell, have attacked the administration's budget outline but have not done enough to link increased military spending and decreased domestic spending.
"That's where we need to hear their voices connecting the dots and speaking out against this out-of-control military spending that doesn't benefit military families," she added. "It only benefits the CEOs of military contractors."
The Trump budget does include a $4.4 billion increase in spending for the Department of Veterans Affairs.
The march is taking place on April 15, typically the day taxes are due. This year the deadline for taxes is Tuesday, April 18.