Volunteers gathered Friday at the Santa Fe National Cemetery to place flags upon gravestones — a tradition that dates to the Civil War.

Among the students participating were those from Gonzales Community School and Mission Viejo Christian Academy. The practice of placing a flag at each headstone happens each Memorial Day weekend at every national cemetery since the Civil War, said Cliff Shields, cemetery director.

On Friday, the 500 volunteers — 400 students and 100 adults — adorned some 37,000 headstones between 9 and 10:30 a.m.

The Santa Fe National Cemetery contains 48,000 deceased veterans and their spouses. The cemetery has enough burial space until 2020, but has plans for expansion and is negotiating with the city for 5.7 acres of land, which it is estimated would extend the burials an additional 15 years.

The Memorial Day ceremony at the cemetery, 501 N. Guadalupe St., is scheduled for 11 a.m. Monday and includes a military flyover and U.S. Sen. Jeff Bingaman as a keynote speaker.

Volunteers also are encouraged to help remove the flags Tuesday.

Most federal, state, city and county government offices, along with courts, public libraries and many businesses, will be closed Monday, and regular mail service will be suspended. The Santa Fe Trails bus system, Santa Fe Ride Service and Rail Runner service also will be suspended in observance of Memorial Day, while city curbside trash collectors will follow their regular schedule.