What is the "slow wheel" in Frost's "Into My Own"?

Question

Into My Own, by Robert Frost (first two stanzas):

One of my wishes is that those dark trees,
So old and firm they scarcely show the breeze,
Were not, as 'twere, the merest mask of gloom,
But stretched away unto the edge of doom.

I should not be withheld but that some day
Into their vastness I should steal away,
Fearless of ever finding open land,
Or highway where the slow wheel pours the sand.

Does anyone have any thoughts on what the "slow wheel" is? All that comes to mind for me is the image of a cart-wheel rolling down an old-school (unpaved) road--which, given the context, makes some sense.

I'd appreciate any thoughts.

Answer 1

Virginia Smith explains in A Scientific Companion to Robert Frost:

highway where the slow wheel pours the sand:
This is most likely a description of the practice of spreading sand on gravel roads to hold down dust during the dry months. At the time the poem was written, fewer than 10 percent of the nation's roads were paved, and the driveway of the Derry farm house is still sand and gravel today. Picture postcards from the early 1900s in Derry show dirt roads in both the town and rural areas. In her diary entry of June 14, 1907, Frost's daughter Lesley writes about the excitement of seeing a different road maintenance vehicle, a steam roller, going down the highway (Londonderry Turnpike) in front of their home.

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You may be interested to know that the original version of the poem used a slightly different wording for that line:

(Frost changed it in later versions.)

Answer 2

I too have wondered about this line. Here's what I've found via internet searches.

The mileage of roads in the United States is so vast and the traffic on many of the country roads is so light that it is out of the question to improve more than a small percentage of these roads with a hard surface. This does not mean, however, that that all other roads must be neglected. They should be improved just as far as their importance and the traffic will warrant. The common clay roads may be vastly improved by a little judicious grading and systematic maintenance.

In many cases, especially in the vast regions of the South, most of the common roads may be improved, for all practical purposes, merely by the addition of sand or clay, as the case may require, and incorporating this with the surface soil of the road. Thousands of miles of sand-clay roads have already been built in the Southern States at an average cost of about $750 per mile. These roads are almost without exception answering the purposes as well as a far more expensive form of construction would do.

The above excerpt comes from: Descriptive Catalogue of the Road Models of the Office of Public Roads. (1913). United States: U.S. Department of Agriculture, Office of Public Roads. (Link to the scanned book.)

The above text also appears in this Scientific American post from 1913, the same year Frost's A Boy's Will was published (though this poem was published elsewhere years before). That Scientific American article has pictures of various forms of road, but I fell asleep before reading it entirely

The 1920s were a "golden age" for road building. In 1922 alone, federal-aid projects totaling 16,500 km were completed at a cost of $189 million, three times as much roadway as had been improved since the start of the federal-aid highway program in 1916. The projects usually involved providing graded earth, sand-clay, or gravel surfaces.

As noted in a comment by @GarethRees, "Spreading sand to suppress dust doesn't seem as if it would work on its own: there would need to be a binder like oil or bitumen." The clay served as a binding agent, as I've read here.

According to that excerpt from highways.dot.gov, it looks like sand-clay roads were a smoother convenience than just gravel. It seems like some sort of wheel would distribute sand onto the roads to improve them. So perhaps helps us understand the speakers fearlessness about never finding "highway where the slow wheel pours the sand."