The National Trust for Historic Preservation has revealed its list of America’s 11 Most Endangered Historic Places for 2009.

On April 28, NTHP president Richard Moe and actor Diane Keaton, an NTHP trustee, delivered the announcement in Los Angeles while standing near the Century Plaza Hotel (1966), a 19-story building by Minoru Yamasaki that is one of the sites on this year’s list. The others include:

• Ames Shovel Shops, Easton, Massachusetts
• Cast-iron architecture of Galveston, Texas
• Dorchester Academy, Midway, Georgia
• Human Services Center, Yankton, South Dakota
• Lāna‘i City, Hawai‘i
• Enola Gay hangar, Wendover Airfield, Utah
• Memorial Bridge, Portsmouth, New Hampshire to Kittery, Maine
• Miami Marine Stadium, Virginia Key, Florida
• Mount Taylor, New Mexico
• Unity Temple, Oak Park, Illinois

The sites on this 22nd annual roster represent various points in the span of American political and social history. The 75-year-old Greek Revival dormitory at Dorchester Academy is the last building at the school, founded for freedman in 1868 and later a center for civil rights–era voter registration drives, for example. Seemingly untouched but threatened by development, the Ames buildings provide a snapshot of New England industry in the 19th century, and the plantation town Lāna‘i City was pineapple baron James Dole’s version of Pullman, Illinois.

Several endangered places also represent 20th-century innovation. Memorial Bridge was the first major lift bridge in the eastern U.S., although cash-strapped state governments have neglected its maintenance; NTHP senior vice president Peter Brink calls current economic conditions “a double-edged sword in terms of preservation,” because recession has relieved certain development pressures but also has complicated fundraising.

More definitively Modernist endangered places include Unity Temple, designed by Frank Lloyd Wright for his Unitarian congregation in Oak Park and dedicated in 1909; it was one of the first public buildings to feature exposed concrete. Miami Marine Stadium was built entirely of poured concrete and features a cantilevered folded-plate roof.

Modernism’s expansive presence on the watch list dovetails with NTHP’s growing interest in recent design and technological feats, and particularly with its Modernism + Recent Past Initiative. Unveiled in mid-April, the initiative will focus on elevating public understanding of architectural works and landscapes constructed within the last 50 years. NTHP’s efforts come at a time when one of the most prevalent concerns of contemporary architecture—sustainable design—is being deployed by developers to justify teardowns. The new owners of Yamasaki’s Century Plaza Hotel, for example, intend to demolish that signature mid-century building for two green towers. “But it is more sustainable to save and retrofit older buildings,” Brink says, “than it is to demolish them, even when building something very green.”

Visit the Trust’s Web site to learn more about the 11 Most Endangered Historic Places campaign.