Built during 1860s

Mason, N. S., House (Bristol County, Massachusetts)
Mason, William P., House (Bristol County, Massachusetts)
Masonic Hall (Madison County, Montana)
Two story Neo-classic Masonic lodge hall built in 1867
Masonic Temple (Huron County, Michigan)
Massaponax Baptist Church (Spotsylvania County, Virginia)
Matheson House (Alachua County, Florida)
Mathewson Block (Caledonia County, Vermont)
Mathias Sharp House (Spencer County, Indiana)
Matthew Baird Mansion (Philadelphia County, Pennsylvania)
Matthew C. Chambers Barn (Linn County, Oregon)
Matthew Keenan Residence (Milwaukee County, Wisconsin)
Edward Townsend Mix design Italianate residence built by the vice president of Northwestern Mutual Life
Matthew Shoecraft House (Oswego County, New York)
Matthias Kremer House (Campbell County, Kentucky)
Mattoon Cabin (Yakima County, Washington)
Maudwin (Noxubee County, Mississippi)
May Street Historic District (Worcester County, Massachusetts)
Mayhurst (Orange County, Virginia)
Maysville Schoolhouse (Franklin County, Iowa)
McAlmond House (Clallam County, Washington)
McCall House (Cumberland County, North Carolina)
McCandless Building (Henry County, Iowa)
McCarty-Lilley House (Sarpy County, Nebraska)
McClellan House (Clear Creek County, Colorado)
McClellan's General Store (Henry County, Iowa)
McClelland-Layne House (Montgomery County, Indiana)
McClellanville Historic District (Charleston County, South Carolina)
McCleod House (Benton County, Arkansas)
McClurg & Ptorney Mercantile (Madison County, Montana)
McComas Institute (Harford County, Maryland)
McCulloch House (McLennan County, Texas)
McCully House (Jackson County, Oregon)
Georgian Revival house built in 1861
McCune's Villa (Licking County, Ohio)
McDonald-Wait-Newton House (Pulaski County, Arkansas)
McDonough County Courthouse (McDonough County, Illinois)
McElroy Octagon House (San Francisco County, California)
McEwen-Samuels-Marr House (Bartholomew County, Indiana)
McGee School (Delaware County, Iowa)
McIntosh Log Church (Washington County, Alabama)
McKinley Fox District (St. Louis, Missouri)
McKinney Mill (Rutherford County, North Carolina)
Historic Grist Mill near Ellenboro, NC
McLemore-Sharpe Farmstead (Toombs County, Georgia)
McMahon House (Dubuque County, Iowa)
Privately owned/occupied home, not open to the public
McMurray House (Williamson County, Texas)
McNiven Farm Complex (Albany County, New York)
McReynolds House (Todd County, Kentucky)
Mead, Alpheus, House (Middlesex County, Massachusetts)
Meadow Grove Farm (Rappahannock County, Virginia)
Means Street Historic District (Fulton County, Georgia)
Mechanics Mill (Bristol County, Massachusetts)
Mechanicsville Covered Bridge (Ashtabula County, Ohio)
Mechanicsville School (Philadelphia County, Pennsylvania)
Mecklenburg's Garden (Hamilton County, Ohio)
Medicine Lodge Peace Treaty Site (Barber County, Kansas)
Medico-Dental Building (San Francisco County, California)
Two story Italianate cast iron facade building built in 1861
Meek Mansion and Carriage House (Alameda County, California)
Meek-Miller House (Jefferson County, Kentucky)
Melges Bakery (Brown County, Minnesota)
Memorial Hall (Norfolk County, Massachusetts)
Memorial Square District (Hampden County, Massachusetts)
Memory Lane (Caroline County, Maryland)
Memphis National Cemetery (Shelby County, Tennessee)
Mendocino Masonic Temple (Mendocino County, California)
Carpenter Gothic fraternal meeting hall built in 1866
Mendocino Presbyterian Church (Mendocino County, California)
Carpenter Gothic church built in 1868
Menlo Park Railroad Station (San Mateo County, California)
Menzo Wheeler House (Jefferson County, New York)
Mercer House (Chatham County, Georgia)
Historic home in Savannah, GA
Meredith Hart House (Johnson County, Texas)
Merrick-Simmons House (Nassau County, Florida)
Merritt Insley House and Outbuildings (Leavenworth County, Kansas)
Metcalfe County Jail (Metcalfe County, Kentucky)
Metcalfe County Kentucky Courthouse (Metcalfe County, Kentucky)
Methodist Episcopal Church (Fairfield County, Connecticut)
Methodist Episcopal Parsonage (Yamhill County, Oregon)
Methodist Parsonage, Old (Lorain County, Ohio)
Metropolitan Savings Bank (New York County, New York)
Meyer House (Scioto County, Ohio)
Michael and Margaritha Beck Farmstead (Jefferson County, Wisconsin)
Michael Crumrine Farm (Ashland County, Ohio)
Michigan Island Lights (Ashland County, Wisconsin)
Two lights, the original was decommisioned in 1929 when a taller skeletal tower was built
Michigan Road Toll House (Marion County, Indiana)
Middle Creek Battlefield (Floyd County, Kentucky)
Middle Island Presbyterian Church (Suffolk County, New York)
Miles House (Davidson County, Tennessee)
Milford Battlefield (Page County, Virginia)
Military Road School (Washington, District of Columbia)
Mill Office and Post Office (Butler County, Ohio)
Mill Rock School (Jackson County, Iowa)
Mill Springs National Cemetery (Pulaski County, Kentucky)
Mill Village Historic District (Berkshire County, Massachusetts)
Millar--Wheeler House (Oneida County, New York)
Miller Building (Clay County, Missouri)
Miller's Mountain House (Douglas County, Oregon)
Miller--Brewer House (Thurston County, Washington)
Miller-Joost House (San Francisco County, California)
Mills River Chapel (Henderson County, North Carolina)
Milton Godard House (Jackson County, Iowa)
Milton State Bank (Caswell County, North Carolina)
Mindrup House--Store (St. Charles County, Missouri)
Mineral County Courthouse (Mineral County, West Virginia)
Minglewood Farm (Montgomery County, Tennessee)
Missionary Ridge Historic District (Hamilton County, Tennessee)
Mitchell J. Green Plantation (Evans County, Georgia)
Mobile and Ohio Railroad Depot (Monroe County, Mississippi)
Model Farm (Guilford County, North Carolina)
Moffett-Ralston House (Owen County, Indiana)
Monitor House (Champaign County, Ohio)
Monocacy National Battlefield (Frederick County, Maryland)
Monohansett Mill (Windham County, Connecticut)
Brick textile mill with central stair tower.
Monongahela Cemetery (Washington County, Pennsylvania)
Monongahela Incline (Allegheny County, Pennsylvania)
Mons Anderson House (La Crosse County, Wisconsin)
Montana Post Newspaper Office (Madison County, Montana)
Gothic style wood and batten newspaper office built in 1864
Monticello Methodist Church (Fairfield County, South Carolina)
Historic church and cemetery in Monticello, SC
Montrest (Putnam County, New York)
Moore Family Farm (Hawkins County, Tennessee)
Moore House (Kent County, Delaware)
Moore House (Putnam County, New York)
Moore-Youse-Maxon House (Delaware County, Indiana)
Mooresville Friends Academy Building (Morgan County, Indiana)
Morgan County Courthouse (Morgan County, Illinois)
Moritz House (Madison County, Montana)
Morrill Hall, Cornell University (Tompkins County, New York)
Morris House (White County, Arkansas)
Morris House (Pickaway County, Ohio)
Morris-Butler House (Marion County, Indiana)
Morrison and Clark Houses (Washington, District of Columbia)
Morrison-Campbell House (Iredell County, North Carolina)
Morse--Scoville House (St. Joseph County, Michigan)
Morse--Skinner Ranch House (San Joaquin County, California)
Mortimer Webster House (Washington County, Minnesota)
Moscow Methodist Church and Cemetery (Nevada County, Arkansas)
Moselem Farms Mill (Berks County, Pennsylvania)
Moses Craig Limekilns (Somerset County, New Jersey)
Moses Rountree House (Wilson County, North Carolina)
Moses--Kent House (Rockingham County, New Hampshire)
Moss-Foster House (Erie County, Ohio)
Mother Of God Roman Catholic Church (Kenton County, Kentucky)
Motor Townsite (Clayton County, Iowa)
Site of a mill complex on the Turkey River, including a reproduced, two-span through truss bridge
Mottley Family Farmstead (Lafayette County, Wisconsin)
Mound Cemetery (Desha County, Arkansas)
Mound City National Cemetery (Pulaski County, Illinois)
Mount Carmel A.M.E. Zion Campground (Lancaster County, South Carolina)
Mount de Chantal Visitation Academy (Ohio County, West Virginia)
Mount Diablo Coal Field (Contra Costa County, California)
Mount Freedom Presbyterian Church (Morris County, New Jersey)
Mount Hebron Temperance Hall (Lexington County, South Carolina)
Mount Olivet Methodist Church (Cleveland County, Arkansas)
Mount Olivet Presbyterian Church (Fairfield County, South Carolina)
Historic church in Fairfield County, SC
Mount Pleasant (Genesee County, New York)
Mount Salem Methodist Episcopal Church (Hunterdon County, New Jersey)
Mount St. Mary's Academy and Convent (Nevada County, California)
Mount Union College District (Stark County, Ohio)
Mount Vernon House (Jefferson County, Colorado)
Mount Zion Presbyterian Church (Muskingum County, Ohio)
Mountview (Williamson County, Tennessee)
Mrs. Margaret Sieben House (Jackson County, Iowa)
Mrs. Slade's House (Madison County, Montana)
Mrs. William R. Reding House (Bastrop County, Texas)
Mt. Airy School No. 27 (New Castle County, Delaware)
Mt. Gilead Baptist Church (Green County, Kentucky)
Muir Church of Christ (Ionia County, Michigan)
Muir House (Cache County, Utah)
Mullanphy Emigrant Home (St. Louis, Missouri)
Mulrien House (Dutchess County, New York)
Mundy-McFarland House (De Soto Parish, Louisiana)
Munger and Company White Store (Madison County, Iowa)
Murphy Varnish Works (Essex County, New Jersey)
Murphys Grammar School (Calaveras County, California)
Murray Hill (Delaware County, New York)
Musconetcong Bridge (Hunterdon County, New Jersey)
Pratt pony truss bridge over Musconetcong River
Musconetcong Bridge (Hunterdon County, New Jersey)
Lowthrop Pratt pony truss bridge over Musconetcong River built by Cowin Iron Works
Myrtle Street School (Hampden County, Massachusetts)
Mystic Dam (Middlesex County, Massachusetts)
Mystic Gatehouse (Middlesex County, Massachusetts)
Mystic Pumping Station (Middlesex County, Massachusetts)
Mystic Water Works (Middlesex County, Massachusetts)
N.H. Gates House (Wasco County, Oregon)
Single story wood frame house built in 1860
Naegle Winery (Washington County, Utah)
Nance-Major House and Store (Charles City County, Virginia)
Napa Valley Railroad Depot (Napa County, California)
Nash-McDonald House (Jefferson County, Kentucky)
Nashville National Cemetery (Davidson County, Tennessee)
Natchez National Cemetery (Adams County, Mississippi)
Nathan B. Devereaux Octagon House (Washtenaw County, Michigan)
Natural Bridge Battlefield (Leon County, Florida)
Naval Armory--Convention Hall (Monroe County, New York)
Navigation Structures at White Lake Harbor (Muskegon County, Michigan)
Naylor House (Polk County, Iowa)
Neal Clothing (Allen County, Ohio)
Neiderhurst (Rockland County, New York)
Nelliston Historic District (Montgomery County, New York)