Lincoln County Poor House Farm (Lincoln County, Tennessee)
Lincoln Elementary School (Delaware County, Iowa)
Lincoln School (Bledsoe County, Tennessee)
Linkous--Kipps House (Montgomery County, Virginia)
Lisbon Opera House (Ransom County, North Dakota)
Lisbon Town Hall (St. Lawrence County, New York)
Little Outfit Schoolhouse, The (Santa Cruz County, Arizona)
Live Oak Historic Commercial District (Sutter County, California)
Livingood House--Stryker Hospital (Berks County, Pennsylvania)
Livingston Parish Courthouse, Old (Livingston Parish, Louisiana)
Locust Creek House Complex (Windsor County, Vermont)
Locust Grove (Loudoun County, Virginia)
Locust Grove (Charlottesville, Virginia)
Lodge Grass Merchandise Company Store (Big Horn County, Montana)
Lodgepole Opera House (Cheyenne County, Nebraska)
Logan Building (Hall County, Georgia)
Logan Furnace Mansion (Centre County, Pennsylvania)
Logan Mills Gristmill (Clinton County, Pennsylvania)
Lone Beech (McDowell County, North Carolina)
Lone Oaks (Roanoke County, Virginia)
Lone Pine (Edgecombe County, North Carolina)
Long Marsh Run Rural Historic District (Clarke County, Virginia)
Long Meadow (Rockingham County, Virginia)
Long Valley Finnish Church (Valley County, Idaho)
Longdon L. Miller Covered Bridge (Washington County, Pennsylvania)
Longs Chapel (Rockingham County, Virginia)
Longwood (Adams County, Mississippi)
Lonsdale Public School (Rice County, Minnesota)
Loretz House (Lincoln County, North Carolina)
Loudon Park National Cemetery (Baltimore, Maryland)
Louis B. Simmons House (Stephens County, Oklahoma)
Louis Bruce Farmstead Historic District (Moniteau County, Missouri)
Lower Parker School (Dent County, Missouri)
Lower Price Hill Historic District (Hamilton County, Ohio)
Lower South Grape Creek School (Gillespie County, Texas)
Lucas Mansion (Alexander County, North Carolina)
Lucius Frierson House (Maury County, Tennessee)
Luckenbach School (Gillespie County, Texas)
Lucky Hit (Clarke County, Virginia)
Lumberton Commercial Historic District (Robeson County, North Carolina)
Lyon County Courthouse (Lyon County, Nevada)
M. C. Mulligan & Sons Quarry (Hunterdon County, New Jersey)
Macedonia Church (Lawrence County, Ohio)
Maddux House (Somerset County, Maryland)
Madison Public Library (Somerset County, Maine)
Madrid Village Schoolhouse (Franklin County, Maine)
Magnolia Grove (Lincoln County, North Carolina)
Magnolia Plantation (Natchitoches Parish, Louisiana)
Maiden Spring (Tazewell County, Virginia)
Main Street Commercial Historic District (Flathead County, Montana)
Main Street Historic District (Berkshire County, Massachusetts)
Main Street Historic District (Wood County, Ohio)
Main Street Historic District (Dutchess County, New York)
Main Street Historic District (Franklin County, Massachusetts)
Main Street Historic District-- Winters (Yolo County, California)
Major John Neff Homestead (Centre County, Pennsylvania)
Mallett Hall (Penobscot County, Maine)
Mammoth Cave Baptist Church and Cemetery (Edmonson County, Kentucky)
Mangum Armory (Greer County, Oklahoma)
Manhattan Laundry (Washington, District of Columbia)
Manhattan School (Nye County, Nevada)
Manitou Fish Camp (Ashland County, Wisconsin)
Restored fish camp on Manitou Island, Apostle Islands National Seashore
Manning Library (Clarendon County, South Carolina)
Mansion at 2401 15th St., NW. (Washington, District of Columbia)
Mansion House (Highland County, Virginia)
Maple Grove Friends Church (Aroostook County, Maine)
Marble Head (Caroline County, Maryland)
Marcus Warren House (Blount County, Tennessee)
Marietta Historic District (Lancaster County, Pennsylvania)
Marion Historic District (Smyth County, Virginia)
Market House (Oswego County, New York)
Market Street Historic District (Wayne County, New York)
Markham Historic District (Fauquier County, Virginia)
Marklesburg Historic District (Huntingdon County, Pennsylvania)
Marquette Hotel (Greene County, Missouri)
Marsh, Joseph and Daniel, House (Windsor County, Vermont)
Martin Hoban House (St. Joseph County, Indiana)
Martin Lindsey House (Mobile County, Alabama)
Martin Marmon House (Logan County, Ohio)
Martinez Canyon Rockhouse (Riverside County, California)
Mary Ann Browne House (Warren County, North Carolina)
Mary Jenkins Community Praise House (Beaufort County, South Carolina)
Mary Lee Davis House (Fairbanks North Star Borough, Alaska)
Mason Brown House (Owen County, Kentucky)
Mason House (Madison County, Kentucky)
Mason Place (Loudon County, Tennessee)
Mason, George G., House (Monroe County, New York)
Mason-Dorton School (Russell County, Virginia)
Mast General Store (Watauga County, North Carolina)
Matt Gardner House (Giles County, Tennessee)
Matthew Lowber House (Kent County, Delaware)
Mauck's Meetinghouse (Page County, Virginia)
Mauk & Hammer/Houghton Elevator (Genesee County, Michigan)
Mauldin House (Habersham County, Georgia)
Maumee Uptown Historic District (Lucas County, Ohio)
Max Baumeister Building (Walla Walla County, Washington)
Mayesville Historic District (Sumter County, South Carolina)
Maynardville State Bank (Union County, Tennessee)
Mayowood Historic District (Olmsted County, Minnesota)
Mays General Store (Searcy County, Arkansas)
Maywood Historic District (Arlington County, Virginia)
McAfee Farm Historic District (Mercer County, Kentucky)
McArthur-Martin Hexadecagon Barn (Delaware County, New York)
McCall District Administrative Site (Payette County, Idaho)
McCauley-Watson House (Alamance County, North Carolina)
McClary House (Kent County, Delaware)
McCleary Farm (Franklin County, Maine)
McClellan House (Clear Creek County, Colorado)
McClelland--Kasuboski House (Green Lake County, Wisconsin)
McClung's Price Place (Kanawha County, West Virginia)
McColloch--Weatherhogg Double House (Allen County, Indiana)
McCollum Farm (Loudon County, Tennessee)
McCoy House (Pendleton County, West Virginia)
McCranie's Turpentine Still (Atkinson County, Georgia)
McCray School (Alamance County, North Carolina)
McCulloch House (McLennan County, Texas)
McCurdy Smokehouse (Washington County, Maine)
McDaniel-Tichenor House (Walton County, Georgia)
McDonald Farm (Greene County, Ohio)
McFarland-Render House (Troup County, Georgia)
McFarlane-Bredt House (Richmond County, New York)
McGehee Plantation (Tate County, Mississippi)
McGuire-Setzer House (Davie County, North Carolina)
McHaffey Opera House (Wapello County, Iowa)
McLeod Farmstead (Beaufort County, South Carolina)
McMurdie--White Farmstead (Cache County, Utah)
McPherson's Purchase (Charles County, Maryland)
Meadea (Clarke County, Virginia)
Meadow Grove Farm (Rappahannock County, Virginia)
Meadows Schoolhouse (Adams County, Idaho)
Mechanicsville Village Historic District (Bucks County, Pennsylvania)
Mechum River Farm (Albemarle County, Virginia)
Meierhoffer House (Cooper County, Missouri)
Melton-Davis House (Rutherford County, North Carolina)
Mercer Street Friends Center (Mercer County, New Jersey)
Mercer Street Historic District (Mercer County, West Virginia)
Mercer Union Meetinghouse (Somerset County, Maine)
Merchants and Planters Bank (Lafourche Parish, Louisiana)
Merkel Mill Complex (Berks County, Pennsylvania)
Mermaid House Hotel (St. Clair County, Illinois)
Merritt-Winstead House (Person County, North Carolina)
Merry Sherwood (Worcester County, Maryland)
Merryall Union Evangelical Society Chapel (Litchfield County, Connecticut)
Merrybrook (Fairfax County, Virginia)
Metcalfe County Jail (Metcalfe County, Kentucky)
Metcalfe Historic District (Thomas County, Georgia)
Methodist Episcopal Church South (Greenup County, Kentucky)
Methodist Episcopal Church, South (Baldwin County, Alabama)
Meusebach Creek School (Gillespie County, Texas)
Meyer Saul House (Hart County, Georgia)
Michael Kinzer House (Montgomery County, Virginia)
Michael Smith House (Braxton County, West Virginia)
Middleburg Historic District (Clay County, Florida)
Middletown Historic District (Frederick County, Virginia)
Miles House (Davidson County, Tennessee)
Mill House (Kent County, Delaware)
Mill Tract Farm (Berks County, Pennsylvania)
Millen High School (Jenkins County, Georgia)
Miller Family Farm (Dickson County, Tennessee)
Miller Homestead (Ashe County, North Carolina)
Miller--Rinehard Farmstead (Morris County, New Jersey)
Miller-Porter-Lacy House (Buchanan County, Missouri)
Mills--Hale--Owen Blocks (Hampden County, Massachusetts)
Milton State Bank (Caswell County, North Carolina)
Miner Normal School (Washington, District of Columbia)
Mineral King Road Cultural Landscape (Tulare County, California)
Minnesota Stoneware Company (Goodhue County, Minnesota)
Minnie Wilkes House (Bastrop County, Texas)
Minnis McCampbell Barn (Blount County, Tennessee)
Minor Sod House (Rawlins County, Kansas)
Mint Saloon (Clear Creek County, Colorado)
Mitchell House (Davidson County, North Carolina)
Mitchell House (Cecil County, Maryland)
Mitchell J. Green Plantation (Evans County, Georgia)
Mitchell Opera House (Lawrence County, Indiana)
Mitchelltown Historic District (Lenoir County, North Carolina)
Mizpah Hotel (Nye County, Nevada)
Moberly House (Madison County, Kentucky)
Modoc Mill (Boulder County, Colorado)
Moeszinger--Marquis Hardware Co. (Clinton County, Iowa)
Hardware vendor repurposed as an office building
Monk House (Claiborne Parish, Louisiana)
Monmouth Street Historic District (Campbell County, Kentucky)
Monroe County Jail (Monroe County, Mississippi)
Montclair Art Museum (Essex County, New Jersey)
Montebello (Charlottesville, Virginia)
Monterey High School (Highland County, Virginia)
Montgomery County Courthouse (Montgomery County, Ohio)
Montgomery Primitive Baptist Church (Montgomery County, Virginia)
Monticello Grange #338 (Aroostook County, Maine)
Montpelier Historic District (Hanover County, Virginia)
Montrose Schoolhouse (Montgomery County, Maryland)