People traveling on Interstate 5 Sunday in and around Vancouver may "feel the Bern" and not even be supporters of the presidential hopeful from Vermont.

Sen. Bernie Sanders will be speaking at a rally at Hudson's Bay High School starting at 1 p.m. Doors open at 11 a.m.

Police say there could be traffic jams from the rally and a downtown Vancouver charity run, the Couve Clover Run, which takes off at 6 a.m. People are encouraged to avoid the areas, take the bus and plan for delays.

"If 500 people show up for the rally, there will be no impact," says Kim Kapp, public information coordinator for the Vancouver Police Department. "If 5,000 people show up, drivers can expect to be sitting at lights" within a three-block radius of the high school at 1601 E. McLoughlin Blvd.

Police do not plan to close street near Hudson's Bay, but traffic may slow down on East McLoughlin Boulevard, East Mill Plain Boulevard and Ft. Vancouver Way as people arrive late morning. Delays are expected again from 2 to 3 p.m., after the rally lets out.

Clark County's bus service C-TRAN recommends rally goers use routes 3, 25, 30 and 37.

Due to the charity run, bus routes 3, 4, 25, 30, 32, 37 and 71 will be detoured from about 6 a.m. to 1 p.m., according to C-TRAN. Detour maps and a full list of stop closures are posted on its website.

"This is an unusual circumstance, and we'll do our best to get you where you need to go," the agency said on its website.

People driving to the rally are advised to carpool and use parking lots and off-street parking outside of the neighborhoods. "Pay attention to the signage," Kapp says.

The rally is one of the Vermont senator's three scheduled appearances Sunday in Washington, according to his campaign website. He also is making stops in Seattle and Spokane. The events come before the Washington Democratic caucuses on March 26.

The event is free and people will be admitted on a first-come basis. Although tickets aren't required, the Sanders camp encourages attendees to

and to bring only small, personal items like keys and cell phones to get through security faster.

Weapons, sharp objects, chairs and signs or banners on sticks will not be allowed, organizers say.

Sanders trails Democratic rival Hillary Clinton in delegate support but is popular in Washington state. The former secretary of state and senator from New York has scheduled appearances in Seattle and Everett on Tuesday.

Sanders last spoke publicly in the Portland area in August, when he addressed a packed crowd at the Moda Center.

A Moda Center official estimated 28,000 people gathered inside and outside the arena. The Hudson's Bay High School gym seats about 4,400.

-- Janet Eastman