Owned by state government

Church of St. Dismas, the Good Thief (Clinton County, New York)
Cincinnati Observatory Building (Hamilton County, Ohio)
Citadel Rock (Chouteau County, Montana)
City Hall Subway Station (IRT) (New York County, New York)
City Hall-Monument District (Hartford County, Connecticut)
City Line Avenue Bridge (Philadelphia County, Pennsylvania)
CITY OF HAWKINSVILLE (shipwreck) (Dixie County, Florida)
City of Rocks (Cassia County, Idaho)
City Waterway Bridge (Pierce County, Washington)
Vertical lift bridge over Foss Waterway on E. 11th Street in Tacoma
Civil War Fortification at Barnesville (Reynolds County, Missouri)
CKW Bridge over Powder River (Sheridan County, Wyoming)
Clarence H. Cooke House (Honolulu County, Hawaii)
Clarence R. Prescott House (Missoula County, Montana)
Clark Hall, University of Virginia (Albemarle County, Virginia)
Clark's Lookout, August 13, 1805 (Beaverhead County, Montana)
Clarkton Bridge (Charlotte County, Virginia)
Clear Creek State Park Family Cabin District (Jefferson County, Pennsylvania)
Clearfield Armory (Clearfield County, Pennsylvania)
Clearfield Farm (New Castle County, Delaware)
Clearing, The (Door County, Wisconsin)
Clemson College Sheep Barn (Pickens County, South Carolina)
Historic Agricultural Building on the campus of Clemson University
Clemson University Historic District I (Pickens County, South Carolina)
Historic college campus district in Clemson, SC
Clemson University Historic District II (Pickens County, South Carolina)
Historic college campus district in Clemson, SC
Clermont (Columbia County, New York)
Clermont (Clarke County, Virginia)
Cleveland-Partlow House (Liberty County, Texas)
Clifton Furnace (Alleghany County, Virginia)
Clinton Armory (Custer County, Oklahoma)
Clinton House (Dutchess County, New York)
Clinton Township Bridge (Venango County, Pennsylvania)
Clover Bottom Mansion (Davidson County, Tennessee)
Clover Lawn (McLean County, Illinois)
Cloyne Court Hotel (Alameda County, California)
Clubhouse--Student Union (Weld County, Colorado)
Cobb Building (King County, Washington)
Col. John Williams House (Knox County, Tennessee)
Colburn Bridge (Rutland County, Vermont)
Colburn House State Historic Site (Kennebec County, Maine)
Cold River Bridge (Rutland County, Vermont)
Cold Spring Bridge (Lehigh County, Pennsylvania)
Cold Springs Pegram Truss Railroad Bridge (Blaine County, Idaho)
Pegram through truss bridge over Big Wood River on a pedestrian trail
College Club House and Gymnasium (Houghton County, Michigan)
College of Medicine of Maryland (Baltimore, Maryland)
College Street Bridge (Warren County, Kentucky)
Pratt through truss bridge over Barren River on College Street
Coloma (El Dorado County, California)
Colorado Governor's Mansion (Denver County, Colorado)
Colorado River Bridge (Mesa County, Colorado)
Two-span through truss over Colorado River on the I-70 Frontage Road (Old US 6)
Colorado River Bridge (Wharton County, Texas)
Colorado River Bridge at Bastrop (Bastrop County, Texas)
Three-span through truss bridge over the Colorado River in Bastrop
Colorado Women's Prison (Fremont County, Colorado)
Colton Point State Park (Tioga County, Pennsylvania)
Columbia Mills Building (Richland County, South Carolina)
Columbia River Bridge at Bridgeport (Unspecified county, Washington)
Columbia River Bridge at Kettle Falls (Ferry County, Washington)
Through truss bridge over Columbia River on US 395
Columbia River Bridge at Northport (Stevens County, Washington)
Through truss bridge over Columbia River on WA 25 in Northport
Columbia River Bridge at Wenatchee (Unspecified county, Washington)
Columbus Loup River Bridge (Platte County, Nebraska)
Columbus-Belmont Civil War State Park (Hickman County, Kentucky)
Combination Shelter (Steuben County, Indiana)
Commandant's Residence Home (Waupaca County, Wisconsin)
Company F State Armory (Middlesex County, Massachusetts)
Comstock Covered Bridge (Middlesex County, Connecticut)
One of three remaining covered bridges in Connecticut
Comstock Hall (Tompkins County, New York)
Conant Creek Pegram Truss Railroad Bridge (Fremont County, Idaho)
Three-span Pegram through truss bridge over Conant Creek
Concourse Yard Entry Buildings (Bronx County, New York)
Concourse Yard Substation (Bronx County, New York)
Coney Island Yard Gatehouse (Kings County, New York)
Confederate Chapel, Cemetery and Cottage (Lafayette County, Missouri)
Confederate Soldiers Monument (Pulaski County, Arkansas)
Confederate State Capitol (Hempstead County, Arkansas)
Connecticut Agricultural Experiment Station (New Haven County, Connecticut)
Connecticut Avenue Bridge (Washington, District of Columbia)
Concrete arch bridge over Rock Creek on Connecticut Avenue
Connecticut General Hospital for the Insane (Middlesex County, Connecticut)
Connecticut State Capitol (Hartford County, Connecticut)
Connecticut Street Armory (Erie County, New York)
Connellsville Armory (Fayette County, Pennsylvania)
Connor Battlefield (Sheridan County, Wyoming)
Connor Hall (Santa Fe County, New Mexico)
Conrad Weiser House (Berks County, Pennsylvania)
Constitution Hall (Fairbanks North Star Borough, Alaska)
Coolidge State Park (Windsor County, Vermont)
Coolidge Sylvan Theatre (Brookings County, South Dakota)
Coombs Village Site (Garfield County, Utah)
Cooper Mansion (Albany County, Wyoming)
Coos Bay Bridge NO. 01823 (Coos County, Oregon)
Steel cantilevered through truss bridge over Coos Bay on US 101 in North Bend
Copake Iron Works Historic District (Columbia County, New York)
Copper Falls State Park (Ashland County, Wisconsin)
Coraopolis Armory (Allegheny County, Pennsylvania)
Cordell Hull Birthplace (Pickett County, Tennessee)
Corduroy Creek Bridge (Navajo County, Arizona)
Corlett Building (Cuyahoga County, Ohio)
Cornell Farmhouse (Queens County, New York)
Corry Armory (Erie County, Pennsylvania)
Cos Cob Railroad Station (Fairfield County, Connecticut)
Cotter Bridge (Baxter County, Arkansas)
Six-span rainbow arch bridge over White River on US 62B at Cotter
Coughlin Campanile (Brookings County, South Dakota)
Council Hall (Salt Lake County, Utah)
County Bridge No. 101 (Chester County, Pennsylvania)
County Bridge No. 124 (Chester County, Pennsylvania)
County Bridge No. 148 (Chester County, Pennsylvania)
County Bridge No. 171 (Chester County, Pennsylvania)
County Bridge No. 36 (Northampton County, Pennsylvania)
County Bridge No. 54 (Montgomery County, Pennsylvania)
Stone arch bridge over Wissahickon Creek on Morris Road near Fort Washington, PA
Courtview (Lauderdale County, Alabama)
Cove Creek Bridge (Conway County, Arkansas)
Through truss bridge over Cove Creek on AR 124
Cove Creek Bridge (Logan County, Arkansas)
Two-span stone arch bridge over Cove Creek on AR 309
Cove Creek Tributary Bridge (Logan County, Arkansas)
Small two-span stone arch bridge over a branch of Cove Creek on AR 309
Cowan Creek Circular Enclosure (Clinton County, Ohio)
Cowell Lime Works Historic District (Santa Cruz County, California)
Cowell Memorial Hospital (Alameda County, California)
Coykendall Lodge (Ulster County, New York)
CQA Four Mile Bridge (Hot Springs County, Wyoming)
Cragfont (Sumner County, Tennessee)
Craigie Flour Mill Historical Marker (Otter Tail County, Minnesota)
Crandall, Prudence, House (Windham County, Connecticut)
Cream Hill Shelter (Litchfield County, Connecticut)
Crisfield Armory (Somerset County, Maryland)
Crites Hall (Dawes County, Nebraska)
Croton Aqueduct, Old (Westchester County, New York)
Crow Wing State Park (Unspecified county, Minnesota)
Crowder State Park Vehicle Bridge (Grundy County, Missouri)
Crowley's Ridge State Park--Bathhouse (Greene County, Arkansas)
Crowley's Ridge State Park--Bridge (Greene County, Arkansas)
Crowley's Ridge State Park--Dining Hall (Greene County, Arkansas)
Crystal Lake State Park (Orleans County, Vermont)
CSS NEUSE (Ironclad Gunboat) (Lenoir County, North Carolina)
Cullars Rotation (Lee County, Alabama)
The oldest ongoing cotton fertility experiment in the United States, the oldest soil fertility experiment in the Southern United States, and the second oldest continuous cotton experiment in the world.
Cumberland Covered Bridge (Grant County, Indiana)
Covered bridge over Mississinewa River on CR 990E in Matthews
Cuming, Dr. John, House (Middlesex County, Massachusetts)
Currituck Beach Lighthouse (Currituck County, North Carolina)
Curry Lookout (Matanuska-Susitna Borough, Alaska)
Curtin Village (Centre County, Pennsylvania)
Curtis Mansion (New Castle County, Delaware)
Curtiss--Wright Hangars 1 and 2 (St. Clair County, Illinois)
Cushing Armory (Payne County, Oklahoma)
Custer State Game Lodge (Custer County, South Dakota)
Custer State Park Museum (Custer County, South Dakota)
Cutting, Bayard, Estate (Suffolk County, New York)
D.H. Lawrence Ranch Historic District (Taos County, New Mexico)
Dade Battlefield Historic Memorial (Sumter County, Florida)
Dads' Gates (Lane County, Oregon)
Dahlonega Courthouse Gold Museum (Lumpkin County, Georgia)
Dairy Building (Beadle County, South Dakota)
Danger Cave (Tooele County, Utah)
DANIEL LYONS (Shipwreck) (Kewaunee County, Wisconsin)
Daniel McCook House (Carroll County, Ohio)
Daniel Royer House (Blair County, Pennsylvania)
Daniel Thompson and Ryle, John, Houses (Passaic County, New Jersey)
Darlington Agency Site (Canadian County, Oklahoma)
Dauberville Bridge (Berks County, Pennsylvania)
David Bradford House (Washington County, Pennsylvania)
David O. Dodd Memorial (Pulaski County, Arkansas)
DAY PECKINPAUGH, (canal motorship) (Niagara County, New York)
De Mores Packing Plant Ruins (Billings County, North Dakota)
Dead Indian Canyon Bridge (Coconino County, Arizona)
Deady Hall (Lane County, Oregon)
DeBary Hall (Volusia County, Florida)
Deception Pass (Skagit County, Washington)
Deep River Freight Station (Middlesex County, Connecticut)
Degnan School (Latimer County, Oklahoma)
Delaware and Raritan Canal (Unspecified county, New Jersey)
Delaware Boundary Markers (Unspecified county, Delaware)
Delaware State Museum Buildings (Kent County, Delaware)
DELUGE (Orleans Parish, Louisiana)
Deming, Richard Henry, House (Providence County, Rhode Island)
Denison House (Luzerne County, Pennsylvania)
Denton Armory (Caroline County, Maryland)
Denton House (Kent County, Maryland)
Dents Run Covered Bridge (Monongalia County, West Virginia)
Covered bridge over Dents Run on CR 43/4
Depoe Bay Bridge No. 01388 (Lincoln County, Oregon)
Deputy Warden's House (Fremont County, Colorado)
Desert Laboratory (Pima County, Arizona)
Detroit Naval Armory (Wayne County, Michigan)
Detroit Observatory (Washtenaw County, Michigan)
Devil's Den State Park Historic District (Washington County, Arkansas)
Dewey Bridge (Grand County, Utah)
wire suspension bridge over Colorado River on UT 128
Dexter Cabin (Lake County, Colorado)
Dickerman Barn (San Mateo County, California)
Dighton Rock (Bristol County, Massachusetts)
Dillon House (Shawnee County, Kansas)
Dinsmoor--Hale House (Cheshire County, New Hampshire)