ALBANY -- New York and Massachusetts are launching an effort to conserve dozens of roadside monuments that mark the route taken by patriots who transported the artillery that forced the British from Boston during the Revolutionary War.

The granite slabs with bronze plaques serve as markers for the Knox Trail, considered one of the earliest heritage trails created in the United States.

The trail mostly follows the original route used by Gen. Henry Knox and his troops in the winter of 1775-76, when the British still occupied Boston.

The Americans lugged 59 captured artillery pieces 250 miles from Fort Ticonderoga to Gen. George Washington's army at Dorchester Heights, overlooking Boston Harbor.

With their army and fleet threatened by Washington's newly arrived cannons and mortars, the British withdrew from Boston on March 17, 1776, celebrated in Boston as Evacuation Day.

"The sheer feat of getting the stuff there is pretty spectacular," said Army Maj. Jason Palmer, who teaches a course on the American Revolution at the U.S. Military Academy.

The markers were originally unveiled in 1927 to commemorate the 150th anniversary of the American Revolution. Thirty were placed in New York and 26 in Massachusetts. Three of New York's markers are missing, but the rest and all of those in the Bay State will be restored, said Mark Castiglione of the Hudson River Valley Greenway National Heritage Area, one of the organizations involved in the project.

"We want to bring the trail back to its former glory," he said.

The restoration project also involves groups in Massachusetts and organizations and state agencies in New York, including the State Office of Parks, Recreation and Historic Preservation, which contributed $25,000.

"Henry Knox and his colleagues enacted one of the enduring epics in our national story," said Wint Aldrich, the park agency's deputy commissioner for historic preservation.

The project is being kicked off Saturday at the monument that serves as New York's marker No. 30 and Massachusetts's marker No. 1.

Located where the state line separates Hillsdale, N.Y., and Alford, Mass., the marker has New York's Knox Trail design on one side and the Massachusetts design on the other.

Saturday's event will include a fife and drum band from Fort Ticonderoga and Revolutionary War re-enactors from the Boston area. The groups will travel back across Massachusetts, stopping at several places along the way for ceremonies, including a groundbreaking for a new marker in Boston's Roxbury section.

Under the guidance of metal-preservation experts with the National Parks Service, the markers' bronze plaques will be cleaned and their surfaces given a new patina to restore them to their original appearance, Castiglione said. The plaques will then be sealed with a coating of hot wax to protect them from the elements.

Getting the cannons and other artillery from the southern shore of Lake Champlain to Washington's army was one of the major engineering feats of the war, Palmer said. To oversee the mission, Washington chose Knox, a 25-year-old bookseller-turned-artillery officer who fought at the Battle of Bunker Hill in 1775.