College students on spring break have joined hundreds of other volunteers at a cemetery dating to the Civil War, realigning hundreds of tilted headstones and scrubbing grime from thousands more.

The cemetery holds the graves of thousands of Union soldiers, and others from later eras.

The volunteers have restored thousands of the roughly 8,000 headstones and other markers at the Chalmette National Cemetery beside the Mississippi River near New Orleans. More than 260 headstones have been put back upright.

More than 150 years after the deadliest conflict on American soil, custodians of many such cemeteries are still doing battle in their upkeep. The cemetery in Louisiana was created in 1864, when Union troops occupied New Orleans. It holds about 6,000 graves of unknown soldiers.