These are two markers noting the location, in Albany County, where the Overland Trail passed by the current town of Laramie.
The Overland Trail was a southern bypass, basically, on the Oregon Trail, taking immigrants and travelers considerably further south and therefore also out of the more active areas on the Platte that saw a lot of Indian activity. The Overland Trail was not safe, but it was less likely to see Indian hostilities.
We tend to think, today, only of the Oregon Trail, but this markers serves to remind us that pioneers took a variety of routes. This one later was exploited, roughly, by the Union Pacific railroad which took a somewhat analogous route for much of its course.
This location interestingly features at least three, and maybe four, generations of Wyoming highway historical markers. The large wooden sign is a common one still used by Wyoming today. A new paper sign with a bar code has been added to this and several other monuments in Albany County, suggesting that the state has some sort of new program going on.
This area, however, also features an older cement marker. I'm not terribly familiar with this type, so if anyone can add details about it, I'd appreciate it. Note the circled K on the monument.
This cement markers is just off the highway easement and I suspect that it is also associated with the trail. In much of Wyoming the Oregon Trail is marked with cement markers in its course, and I suspect that this is something similar, but older, for the Overland Trail.