The Transcontinental Airway System was a navigational aid system built in the 1920s and 1930s.

These beacons allowed for day and night navigation across the country, there were 284 beacons built to guide the airmail with some of them using concrete arrows to point the way to the next beacon.

Someone who’s done much more work thanI have so far has their list here.

The sites I’ve documented are linked below:

Contract Air Mail Route #4 Los Angeles-Salt Lake

• 36 LA-SL Motoqua
• 37 LA-SL Hebron
• 37A LA-SL St. George
• 37A LA-SL Bloomington Overlook
• 37B LA-SL Shinob Kibe
• 38 LA-SL Quail Creek
• 40A LA-SL Black Ridge
• 44 LA-SL Milford
• 44 LA-SL Picacho Peak
• 49 LA-SL Borden
• 50 LA-SL Clear Lake
• 50 LA-SL Sunstone Knoll
• 59 LA-SL Stockton
• 60 LA-SL Tickville Springs

Contract Air Mail Route #5 Elko-Pasco / Salt Lake-Pasco / Salt Lake-Pendleton Airway

• 2 SL-P Antelope Island N.
• 4 SL-P Indian Cove
• 6 SL-P Rozel Point
• 7 SL-P Locomotive Springs

Contract Air Mail Route #18 San Francisco-Salt Lake / Salt Lake-Omaha Airway

• 55 SF-SL Barro
• 18_57 SF-SL Low
• 18_59 SF-SL Poverty Point
• 18_61A SF-SL Lake Point
• 1A SL-O Fort Douglas / Big Beacon / Wire Mt.
• SL-O Great Western Trail
• SL-O Big Dutch Hollow
• 4 SL-O Upton
• SL-O Red Hole S

Contract Air Mail Route #26 Salt Lake-Great Falls

• 26 SL-GF Farmington
• 5B SL-GF Brigham

Los Angeles-Denver Airway

• 45 LA-D Bryce Canyon CAA
• Hanksville
• Canyonlands

Unknown Airway / Airport

• Michael AFB
• Bolinder Tooele Valley
• Carbon County (PUC) / Buck Davis Field
• Green River Municipal (RVR)
• Jean Nevada
• Kanab Municipal (KNB)
• Logan-Cache Airport
• Richfield Municipal (RIF)
• South Valley Regional Airport
• Spanish Fork Springville

Other interesting info:

• Arrows Across America
• The Forgotten Giant Arrows that Guide you Across America