Every year since 1988, Washington, D.C.–based nonprofit National Trust for Historic Preservation (NTHP) has named endangered historic places under its America's 11 Most Endangered Historic Places program. To date, the NTHP has raised awareness about nearly 300 historic sites, from which, according to the group, "only a handful of sites have been lost." This year's list includes a diverse host of nation's most important architectural and cultural heritage facing irreparable damage or destruction, ranging from deferred maintenance to inappropriate development to destruction by natural disasters. This year also marks the third time that a 12th site is placed on the "Watch Status," meaning that "a specific threat to a historic site appears to be growing, but can be avoided or controlled through collaboration and innovation," according to the NTHP.

Here are this year's America’s 11 Most Endangered Historic Places:

Courtesy CMT Group 1/National Trust for Historic Preservation

Annapolis’ City Dock Area in Annapolis
A rezoning proposal for the Colonial Annapolis Historic District has overpass preservation regulations that have been in place for more than 45 years. According to the Trust, the proposal threatens to damage life quality and heritage tourism economy, "as well as permanently diminish its charm and unparalleled views."

Carol High Smith/Courtesy National Trust for Historic Preservation

Ashley River Historic District in Charleston County, S.C.
The historic district represents South Carolina's rich cultural heritage. Now, an annexation proposal might lead to zoning changes and is likely to threaten to impose an irreparable damage to the Palmetto State's historic landscape.

Courtesy BVH Architecture/National Trust for Historic Preservation

Dr. Susan LaFlesche Picotte Memorial Hospital in Walthill, Neb.
Named after Susan La Flesche Picotte, the first Native American to earn a medical degree in the United States, the eponymous memorial hospital, which opened in 1912, is believed to be the first hospital built for any Indian reservation without federal funding, according to the NTHP. A National Historic Landmark since 1993, the 106-year-old former hospital is currently unoccupied.

Courtesy Para la Naturaleza/National Trust for Historic Preservation
Gerville Larsen/Courtesy National Trust for Historic Preservation

Historic Resources of Puerto Rico and the U.S. Virgin Islands.
Damaged by the 2017 hurricanes, thousands of Puerto Rico and the U.S. Virgin Islands' historic and cultural resources are facing challenges due to limited resources and preservation expertise.

Courtesy Mississippi Heritage Trust/National Trust for Historic Preservation

Isaiah T. Montgomery House in Mound Bayou, Miss.
Built in 1910, the historic house was the home of former slave Isaiah T. Montgomery. The house is currently in need of stabilization and rehabilitation.

Courtesy Historic Denver/National Trust for Historic Preservation

Larimer Square in Denver
Larimer Square is considered Denver's first commercial block and first historic district. The neighborhood, according to the NTHP, "has for decades been a pioneering national model for revitalizing neighborhoods through preservation." However, it is now threatened by a development proposal that requires partial demolition of several historic buildings.

Jordan Sorenson/Courtesy National Trust for Historic Preservation

Mary and Eliza Freeman Houses in Bridgeport, Conn.
Regarded as the oldest houses built by African-Americans in the Constitution State, the Freeman Houses help to highlight the story of the free black community in the pre-Civil War area. The houses are in deteriorating conditions and have been vacant for years.

Courtesy George Washington's Mount Vernon/National Trust for Historic Preservation

Mount Vernon and Piscataway National Park in Mount Vernon, Va.
Dominion Energy, a Richmond, Va.–based American power and energy company, has proposed constructing a gas compressor station adjacent to the Piscataway National Park, which eventually will obstruct historic views from George Washington's estate. The proposal also threatens the natural beauty of Piscataway National Park across the Potomac River in Maryland, according to the NTHP.

The Lyda Hill Texas Collection of Photographs in Carol M. Highsmith's America Project, Library of Congress/Courtesy National Trust for Historic Preservation

Route 66 in Multiple States
America’s “Mother Road,” Route 66 is widely known as "our nation’s romance with the open road," states the NTHP. In order to bring wider recognition and economic development to the historic trail, a legislation must be passed by the U.S. Senate and signed by the president before the end of 2018 to designate Route 66 a National Historic Trail, otherwise, preservation opportunities may be lost, according to the Trust.

Julie McGilvray/Courtesy National Trust for Historic Preservation

Ship on the Desert in Salt Flat, Texas
Designed by Long Island–based architect couple Elizabeth and Newton Bevin, the Ship on the Desert house was the home of the Wallace Pratt, a pioneer American petroleum geologist. Completed in 1943, this early modernist house is in a deteriorating condition, and not open to the public, according to the NTHP.

Courtesy LA Conservancy/National Trust for Historic Preservation

Walkout Schools of Los Angeles in California
These historic campuses have played an important role in the 1968 East LA walkouts, a series of protests by Mexican-American students against discriminating conditions in Los Angeles Unified School District high schools in California, which according to the Trust, "helped catalyze the national Chicano Civil Rights Movement." All five historic schools are now facing demolition threats by the school district. The schools are: James A. Garfield High School, Theodore Roosevelt High School, Abraham Lincoln High School, Belmont High School, and El Sereno Middle School (formerly known as Woodrow Wilson High School).

Watch Status Site:

Brenda Petrella/Courtesy National Trust for Historic Preservation

Four Towns of Vermont’s Upper Valley (in Royalton, Sharon, Strafford, and Tunbridge)
A development proposal, calling for construction of a new planned community in this rural part of Vermont, threatens the village centers and the surrounding farms and forests.

Last year's list included President Lincoln's Cottage at the Soldiers' Home in Washington, D.C.; Little Rock Central High School in Little Rock, Ark.; New York's Governors Island National Monument; and Antietam National Battlefield Park in Sharpsburg, Md.