Built during 1930s

Olympus Guard Station (Jefferson County, Washington)
Onamia Municipal Hall (Mille Lacs County, Minnesota)
One LaSalle Street Building (Cook County, Illinois)
Oneida Armory (Madison County, New York)
Oneida County Courthouse (Oneida County, Idaho)
Ong Yut Geong Wholesale Market (Maricopa County, Arizona)
Opelousas City Hall (St. Landry Parish, Louisiana)
Opus 40 (Ulster County, New York)
Oregon Caves Chateau (Josephine County, Oregon)
Oregon State Capitol (Marion County, Oregon)
Oroville Inn (Butte County, California)
Orpheum Theater (Clarion County, Pennsylvania)
Orr Roadside Parking Area (St. Louis County, Minnesota)
Orson Ames House (Oswego County, New York)
Orville Jackson House (Ada County, Idaho)
Osage Farms Unit No. 31 (Pettis County, Missouri)
Osage Farms Unit No. 41 (Pettis County, Missouri)
Oscar C. Diehl House (Midland County, Michigan)
Oscar Carlson House (Morris County, Kansas)
Oskar G. Stonorov House (Chester County, Pennsylvania)
Ossoli Circle Clubhouse (Knox County, Tennessee)
Osterman's Shell Station (Mohave County, Arizona)
Oswego West Pierhead Lighthouse (Oswego County, New York)
Ottauquechee River Bridge (Windsor County, Vermont)
Ottawa Street Power Station (Ingham County, Michigan)
Municipal electric and steam generating power plant
Otter Creek Bridge (Chautauqua County, Kansas)
Through truss bridge over Otter Creek, 4.2 mi. north of Cedarvale
Otter Spring House (Forest County, Wisconsin)
Ouachita County Courthouse (Ouachita County, Arkansas)
Our Lady of Grace Church (St. John the Baptist Parish, Louisiana)
Our Lady of Mount Carmel Grotto (Richmond County, New York)
Our Lady of the Assumption School (Lafayette Parish, Louisiana)
Our Lady Sorrows Catholic Church (Sweetwater County, Wyoming)
Our Mother of Mercy School (Tarrant County, Texas)
Our Savior's Lutheran Church (Yankton County, South Dakota)
Overton Gymnasium (Clark County, Nevada)
Overton Theatre (Rusk County, Texas)
Owen Park Bandshell (Eau Claire County, Wisconsin)
The name says it all
Owyhee County Courthouse (Owyhee County, Idaho)
Ox Bow Inn (Gila County, Arizona)
Oyster Point Historic District (New Haven County, Connecticut)
Ozark Community Building (Christian County, Missouri)
P. K. Yonge Laboratory School, Old (Alachua County, Florida)
P. S. Dupont High School (New Castle County, Delaware)
Pacific Biological Laboratories (Monterey County, California)
Page County Bridge No. 1990 (Page County, Virginia)
Page Theater (Page County, Virginia)
Painted Desert Inn (Apache County, Arizona)
Painted Desert Inn (Apache County, Arizona)
Paintsville City Hall (Johnson County, Kentucky)
Paintsville Country Club (Johnson County, Kentucky)
Paintsville Public Library (Johnson County, Kentucky)
Pal Theater (Toombs County, Georgia)
Palace of Fine and Decorative Arts, Treasure Island (San Francisco County, California)
Palace Theater (Cumberland County, Tennessee)
Palace Theater (Cabarrus County, North Carolina)
Palace Theater (Blount County, Tennessee)
Palace Theater (Childress County, Texas)
Palace Theatre (Albany County, New York)
Palisade Interstate Parkway (Bergen County, New Jersey)
Palmer Brook Bridge (Clinton County, New York)
Palmer Depot (Matanuska-Susitna Borough, Alaska)
Palmer Fire School (Mecklenburg County, North Carolina)
Palos Verdes Public Library and Art Gallery (Los Angeles County, California)
Pamlico County Courthouse (Pamlico County, North Carolina)
Pampa City Hall (Gray County, Texas)
Panola High School and Gymnasium (Latimer County, Oklahoma)
Pantops Farm (Albemarle County, Virginia)
Parachute Jump (Kings County, New York)
Paradise Valley Ranger Station (Humboldt County, Nevada)
Paradise Water Tower (Russell County, Kansas)
Paramount Theater (Denver County, Colorado)
Paramount Theater (Potter County, Texas)
Paramount Theater (Albemarle County, Virginia)
Paramount Theater (Pitt County, North Carolina)
Paramount Theater (Jefferson County, Colorado)
Paramount Theatre (Alameda County, California)
Paramount Theatre (Boyd County, Kentucky)
Paramount Theatre (Kane County, Illinois)
Paramount Theatre (Williams County, Ohio)
Paramount Theatre (Harrison County, Texas)
Paramount Theatre and Office Building (Sullivan County, Tennessee)
Parents' and Children's Schoolhouse (Midland County, Michigan)
Paris Post Office (Logan County, Arkansas)
Park Butte Lookout (Whatcom County, Washington)
Park Falls Post Office (Price County, Wisconsin)
Park Hotel (Garland County, Arkansas)
Park Lake Historic District (Guadalupe County, New Mexico)
Park Theater (Hubbard County, Minnesota)
Park Vista and Pine Manor Apartments (Washington, District of Columbia)
Parkdale Ranger Station (Hood River County, Oregon)
Parker Dam State Park - Octagonal Lodge (Clearfield County, Pennsylvania)
8-sided cabin within Parker's Dam State Park
Parker Dam State Park - Parker Dam District (Clearfield County, Pennsylvania)
Parker Dam State Park Family Cabin District (Clearfield County, Pennsylvania)
Parker High School Auditorium (Greenville County, South Carolina)
Parker Meadows Shelter (Jackson County, Oregon)
Parkway Theater (Hennepin County, Minnesota)
Parnell Hall (Pulaski County, Arkansas)
Parnell--Sharpe House (Desha County, Arkansas)
Parry Lodge (Kane County, Utah)
Pass Creek Snowshoe Cabin (Flathead County, Montana)
Patten Colony Farm (Matanuska-Susitna Borough, Alaska)
Paugnut Forest Administration Building (Litchfield County, Connecticut)
Paul Bunyan and Babe the Blue Ox (Beltrami County, Minnesota)
Paul F. Murphy House (Multnomah County, Oregon)
Paul Lawrence Dunbar School (Philadelphia County, Pennsylvania)
Paul Schweikher House and Studio (Cook County, Illinois)
Paulina Lake Guard Station (Deschutes County, Oregon)
Pauline Cheek Barton House (Shelby County, Tennessee)
Pawhuska Armory (Osage County, Oklahoma)
Pawhuska Post Office (Osage County, Oklahoma)
Pawnee Armory (Pawnee County, Oklahoma)
Pawnee County Courthouse (Pawnee County, Oklahoma)
Pawtucket City Hall (Providence County, Rhode Island)
Pawtucket West High School (Providence County, Rhode Island)
Peabody School (Dodge County, Georgia)
Peace and Harvest (Peoria County, Illinois)
Peach County Courthouse (Peach County, Georgia)
Pear Lake Ski Hut (Tulare County, California)
Pearl High School (Davidson County, Tennessee)
Pearl Street School (Middlesex County, Massachusetts)
Pebble Hill Plantation (Unspecified county, Georgia)
Pecue House (East Baton Rouge Parish, Louisiana)
Pedro de Lemos House (Santa Clara County, California)
Pee Dee Avenue Historic District (Stanly County, North Carolina)
Peggy Ann Building (Mahoning County, Ohio)
Pellissier Building (Los Angeles County, California)
Pelton Creek Shelter (Jefferson County, Washington)
Pembroke High School, Former (Robeson County, North Carolina)
Pender County Courthouse (Pender County, North Carolina)
Pengra Covered Bridge (Lane County, Oregon)
Covered bridge over Fall Creek on Place Road
Penn Theater (Butler County, Pennsylvania)
Penn Theater (Berks County, Pennsylvania)
Pennsylvania Station (Essex County, New Jersey)
Pensacola Dam (Mayes County, Oklahoma)
Dam carrying S.H. 28 over Neosho (Grand) River between Langley & Disney.
People's Bank (Hancock County, West Virginia)
People's National Bank Building (Smith County, Texas)
Peoples Forest Museum (Litchfield County, Connecticut)
Peoria Lock and Dam Historic District (Tazewell County, Illinois)
Perry Armory (Noble County, Oklahoma)
Perry Avenue Historic District (Worcester County, Massachusetts)
Perry County Courthouse (Perry County, Illinois)
Perry Creek Shelter (Whatcom County, Washington)
Perry Post Office, Old (Taylor County, Florida)
Perry, C. W. Archie--Hallmark House (Angelina County, Texas)
Perryville American Legion Building (Perry County, Arkansas)
Person County Courthouse (Person County, North Carolina)
Petit Jean River Bridge (Logan County, Arkansas)
Through truss bridge over Petit Jean River on Old AR 109 (CR 277) south of Magazine
Petit Jean State Park--Cabin No. 1 (Conway County, Arkansas)
Petit Jean State Park--Cabin No. 16 (Conway County, Arkansas)
Petit Jean State Park--Cabin No. 6 (Conway County, Arkansas)
Petit Jean State Park--Cabin No. 9 (Conway County, Arkansas)
Petit Jean State Park--Culvert No. 1 (Conway County, Arkansas)
Petit Jean State Park--Mather Lodge (Conway County, Arkansas)
Phi Delta Theta Fraternity House (Lancaster County, Nebraska)
Philadelphia High School for Girls (Philadelphia County, Pennsylvania)
Philadelphia Savings Fund Society Building (Philadelphia County, Pennsylvania)
Philadelphia School of Occupational Therapy (Philadelphia County, Pennsylvania)
Philip D. Armour III, House (Lake County, Illinois)
Phillip 66 (Crawford County, Missouri)
Phillips 66 Service (Laclede County, Missouri)
Phillips 66 Station No. 1423 (Lincoln County, Oklahoma)
Phillips Brothers Mill (Shasta County, California)
Phillips County Courthouse (Phillips County, Colorado)
Phillips Memorial Auditorium (Perry County, Alabama)
Phoenix Homesteads Historic District (Maricopa County, Arizona)
Piccardy Apartments (Salt Lake County, Utah)
Pickett County Courthouse (Pickett County, Tennessee)
Pickwick (Chester County, Pennsylvania)
Picnic Area-Jackson State Forest (Jackson County, Indiana)