2 BULLETIN" 249, U. S. DEPARTMENT OP AGRICULTURE. 
to 1909 the total area of concrete pavements which had been con- 
structed in this country was comparatively small, and in the majority 
of cases these pavements were frankly regarded as experiments. 
During 1909 the road officials of several communities concluded that 
the results already obtained were sufficiently encouraging to warrant 
them in undertaking the construction of concrete roads on a larger 
scale, and since that time many such roads have been completed. 
Wayne County, Mich., was one of the first communities to adopt this 
form of construction and at present probably has a greater mileage 
of roads paved with concrete than any other county in the United 
States. 
The fact that the majority of the concrete pavements which have 
been constructed have proved entirely satisfactory where traffic con- 
ditions were not unduly severe is serving to increase their popularity 
very rapidly. This is evidenced by the following tabulation, showing 
the approximate number of square yards of such pavements that have 
been constructed in the United States each year beginning with 1909 : 
Square yards. 
1909 364. 000 
1910 S50. 000 
1911 1, S00, 000 
1912 6. 470, 000 
1913 . , 10. 100. 000 
1914 (estimated) 19, 200. 000 
Enthusiastic advocates of concrete roads should bear in mind that 
such roads can never be economically adapted to all traffic conditions, 
and those who are in responsible charge of road-improvement work 
should realize the importance of making a careful economic compari- 
son of the various kinds of road surfaces under the conditions to be 
met before deciding upon the type of improvement to adopt. 
The principal advantages which concrete pavements possess may 
be briefly stated and commented upon as follows : 
1. As far as can be judged, they are durable under ordinary subur- 
ban and rural traffic conditions. While it is true that there are no 
very old concrete pavements in existence, the present condition of 
many of those which have undergone several years' service would 
seem to warrant the above statement. 
2. They present a smooth, even surface, which offers very little re- 
sistance to traffic. In the past the surfaces of concrete pavements 
have sometimes been roughened in order to insure a good foothold 
for horses. This practice has now been abandoned, except on very 
steep grades, because it tends greatly to accelerate deterioration of 
the pavement, and because the smooth surface has been found to 
afford a fairly satisfactory foothold under all ordinary conditions. 
3. They produce practically no dust and may be easily cleaned. 
