Yes, US 12 is a highway. A two lane highway going through some beautiful hilly countryside.
No, the towers are not lighthouses, they are wooden observation towers built in the 1920s to promote tourism to the area. They have fallen into disrepair and, according to someone who stopped to talk to me when they saw me taking pictures, they are scheduled to be demolished. The area used to have lots of neat tourist traps -- A Mystery Spot, a dinosaur park (now fenced off, or I'd go explore), a (fake) frontier town, and a campground or two.
What with you reading LJ on your blackberry, my scrapbook pages may be too small for you to make out the details, but the towers are missing parts of their siding, some of the windows are boarded up, etc. Here's another page showing just one of the towers.