I wondered why the town hadn't been dug up but some Googling revealed that they have horizontal drilling machines for this job.
I took a different route home and noticed that there was some new road paint. In addition to new dashed white lines (not shown), someone had spray-painted MH next to a BellSouth manhole cover.
A manhole cover directly across the street from my yard.
This photo doesn't show the fiberglass junction box nearby, or the fiber optic cable on a utility pole. The cable on the pole leads into the ground near the fiberglass box. There are a bunch of poles carrying fiber optic cable around this part of town. I saw an AT&T truck putting new fiber on the poles several months ago, and the manhole cover has a BellSouth logo so I believe this section is managed by them. With all of this infrastructure available right by my yard, I wonder why AT&T refuses to connect me to their fiber.
Anyway, I don't think it's a coincidence that the paint appeared at the same time as those tubes.
Today I went to check if anything had happened and, to my surprise, there was a call-before-you-dig marker beside a new fiberglass junction box set partway into the sidewalk.
Apparently this is being done by the Palmetto Rural Telephone Co-op, a company I hadn't heard of before.
This is only 1/4 mile from my house so perhaps the neighborhood will be offered better Internet service. I can't imagine why a small-town post office, or any post office for that matter, would need its own dedicated fiber lines.