Historical Statistics of the United States Millennial Edition Online

		Df184	Df185	Df186
		Total	Under state control
		High-type roads	Low-type roads
Row	Year	Thousand miles	Thousand miles	Thousand miles
1	1904	154	----	----
2	1905	161	----	----
3	1906	168	----	----
4	1907	176	----	----
5	1908	183	----	----

6	1909	190	----	----
7	1910	204	----	----
8	1911	217	----	----
9	1912	231	----	----
10	1913	244	----	----

11	1914	257	----	----
12	1915	276	----	----
13	1916	295	----	----
14	1917	313	----	----
15	1918	332	----	----

16	1919	350	----	----
17	1920	369	----	----
18	1921	387	----	----
19	1922	412	----	----
20	1923	439	34	78

21	1924	472	41	90
22	1925	521	48	97
23	1926	550	54	109
24	1927	589	60	117
25	1928	626	68	125

26	1929	662	75	133
27	1930	694	84	142
28	1931	830	96	146
29	1932	879	110	156
30	1933	914	116	195

31	1934	992	124	237
32	1935	1,080	128	246
33	1936	1,175	131	262
34	1937	1,232	144	265
35	1938	1,276	149	277

36	1939	1,318	151	286
37	1940	1,367	153	296
38	1941	1,608	163	297
39	1942	1,630	165	302
40	1943	1,646	166	306

41	1944	1,655	167	309
42	1945	1,721	168	312
43	1946	1,730	170	317
44	1947	1,780	170	332
45	1948	1,815	172	338

46	1949	1,865	174	350
47	1950	1,939	227	316
48	1951	1,998	236	323
49	1952	2,070	245	328
50	1953	2,160	252	332

51	1954	2,228	262	333
52	1955	2,273	270	340
53	1956	2,323	281	335
54	1957	2,371	290	338
55	1958	2,448	301	338

56	1959	2,503	314	338
57	1960	2,557	322	338
58	1961	2,588	331	338
59	1962	2,647	341	337
60	1963	2,693	350	336

61	1964	2,730	359	334
62	1965	2,776	367	333
63	1966	2,800	376	334
64	1967	2,827	386	331
65	1968	2,870	392	330

66	1969	2,914	403	324
67	1970	2,946	411	322
68	1971	2,983	419	319
69	1972	3,021	426	316
70	1973	3,042	431	312

71	1974	3,067	432	308
72	1975	3,101	433	311
73	1976	3,135	439	307
74	1977	3,164	432	309
75	1978	3,203	441	302

76	1979	3,167	449	286