At dawn on November 29, on the 150th anniversary of the Sand Creek Massacre, more than 500 descendants of massacre survivors and other tribal members gathered on Monument Hill for private ceremonies commemorating their fallen ancestors. Meanwhile, down below at the headquarters of the Sand Creek Massacre National Historic Site, which was dedicated in April 2007, hundreds of other people arrived to remember -- or perhaps hear for the first time -- what had happened on November 29, 1864, when Colonel John Chivington led 675 volunteers and regular Army troops on that bloody raid of a peaceful camp, a chief's camp that was supposed to be under the protection of the U.S. government, and killed up to 200 Cheyenne and Arapaho, most of them women, children or elderly men.

See also: Sand Creek Massacre -- Governor John Hickenlooper's Apology, Story Behind It

While the private tribal ceremonies continued, National Parks Service rangers offered lectures, and then came the speeches, including one from Senator-elect Cory Gardner, who is helping to push for federal funding of a Sand Creek visitors' center in downtown Eads.

Eads can certainly use any economic boost it can get. This prairie town twenty-plus miles southwest of the massacre site has been losing population for decades, and is still in the grip of drought. Beyond filling Eads's single restaurant and its new motel, the Sand Creek commemoration activities didn't add much to the town's coffers; that visitors' center is still several years and at least several hundred thousand dollars away from completion. But the town wanted to make its mark on the anniversary, and so after strategizing with the National Park Service, which operates the massacre site, the manager of the local post office set up a stand where visitors could get a special Sand Creek cancellation that morning.

"Done right, they can really be a great collector's piece," says David Rupert, spokesman for the U.S. Postal Service's Western Area region, which signed off on the project. "It adds to the event."

Was this cancellation done right? The enabling legislation that created the Sand Creek Massacre National Historic site makes it clear that tribal representatives are supposed to be consulted every step of the way by federal agencies, including the NPS, which did so much to organize the successful commemoration events. (The still-closed exhibit space at the History Colorado Center once filled by Collision, a controversial display devoted to the Sand Creek Massacre, is testament to what can happen when a government entity fails to consult with the tribes.) And the logo used on the commemorative envelope -- tepee poles topped by an American flag and a white flag, both of which were flying at the camp that day but failed to dissuade Chivington's men -- was a variation on the tribe-approved art for the anniversary. But tribal representatives say they had no idea the USPS was offering special commemorative cancellations while their ceremonies were under way up on Monument Hill.

The USPS was selling those envelopes with a special cancellation for $10 each. But there was no charge for the standard U.S. postal service bag that came with it, encouraging you to "Collect U.S. Commemoratives -- they're fun, they're history, they're America."

Is remembering a massacre fun? No. But it was America all the way. And so was the fact that one collector who mailed off a commemorative envelope found that his post office had added an unnecessary seasonal snowman cancellation to make his collectable just a little more special -- and a lot less valuable.

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