Wikipedia:WikiProject U.S. Roads/Colorado/All-time list

Given are the years of the first and last official maps the routes appear on (latest I have is 2006). These are not always the exact years the routes were created or eliminated.

Note: Highways 200-233 page on mesalek.com is missing.

The following don't quite fit into the 1938 clustering:
 * Probably missing routes
 * The first number to be reused was 107 in 1932 (first one disappeared 1926); 128 (disappeared 1930) waited until 1936.
 * Just before 1939, all numbers from 50 to 189 have been found except:
 * 85 (renumbered 189 because it touched US 85)
 * 182, 184, 188 (even numbers ended with 180, except that 186 was assigned at the same time as 185)
 * 178 (unlabeled, but location suggested below)
 * Additionally, I haven't found a pre-1939 18, even though 20 and 22 existed.
 * After the large expansion in 1939, all numbers from 1 to 378 have been found. The following are unlabeled:
 * 178 (can't find it anywhere on any map; location suggested below)
 * 230 (doesn't appear until 1940; location suggested below)
 * 266 (doesn't appear until 1940; location suggested below)
 * 271 (doesn't appear until 1945; location suggested below)
 * 319 (doesn't appear until 1942; location suggested below)
 * 336 (doesn't appear until 1942; location suggested below)
 * Why were some numbers (200, 218, 266, 355) reused in 1949-1951 and others were not? (243, 250, 261); 243's location is suggested below
 * After the large cutback in 1953, all numbers from 1 to 30 were used except:
 * 11 (doesn't appear until 1959)
 * 18 (doesn't appear until 1958)
 * 20 (doesn't appear until 1956, but was likely proposed 1952)
 * 29 (doesn't appear until 1964)
 * Finally, in 1968, everything from 1 to 33 except 21 was used, as were even numbers up to 42 except 34.
 * Out-of-place routes
 * 225: near 207-215
 * 237: near 369-377
 * 243-245: near 221-223; but also near 246
 * 299: near 265-269
 * 305: near 241-247
 * 309: near 241-247
 * 331: near 355-361
 * 182-184: probably added before 1938
 * 240: near 254-256
 * 246: near 220-224; but also near 243-245
 * 284: near 364-366
 * 308: near 312-314
 * 328: near 306; but also near 327
 * 334: near 286
 * 344: near 220-224