Prototype History: Production of the 4650-cubic foot 3-bay cars began in 1964. ACF built 2504 examples at Huntington, WV, between 1964 and 1972. The ACF 4650 c.f. 3-bay hopper was the same height and width as the 5250 c.f. 4-bay car but several feet shorter in length (and only had 3 bays!). Some railroads that were not concerned about having the larger plate C clearance 4650cf cars (which could not be used on all branchlines or at all loading facilities) opted for large fleets of 4650cf cars instead of 4600cf. UP and SP were two such railroads (all of the current UP 4600cf cars came from either MP or C&NW heritage).

Hatches: 6 30", 6 20", 3 pressed steel elongated (SP, SSW, 3 piece pressed steel continuous or 4 piece FRP continuous. Outlets: Several types of bolted or welded on outlets are used. Uses: Grain, soda ash, platic pellets. Trucks: 77 ton friction or roller bearing. 86 had 100 ton roller bearing.

Road Name History: The Illinois Central Railroad (reporting mark IC), sometimes called the Main Line of Mid-America, was a railroad in the central United States, with its primary routes connecting Chicago, Illinois, with New Orleans, Louisiana, and Mobile, Alabama. A line also connected Chicago with Sioux City, Iowa (1870). There was a significant branch to Omaha, Nebraska (1899), west of Fort Dodge, Iowa, and another branch reaching Sioux Falls, South Dakota (1877), starting from Cherokee, Iowa. The Sioux Falls branch has been abandoned in its entirety.

The IC is one of the early Class I railroads in the US. Its roots go back to abortive attempts by the Illinois General Assembly to charter a railroad linking the northern and southern parts of the state of Illinois. In 1850 U.S. President Millard Fillmore signed a land grant for the construction of the railroad, making the Illinois Central the first land-grant railroad in the United States.

The Illinois Central was chartered by the Illinois General Assembly on February 10, 1851. Senator Stephen Douglas and later President Abraham Lincoln were both Illinois Central men who lobbied for it. Douglas owned land near the terminal in Chicago. Lincoln was a lawyer for the railroad. Upon its completion in 1856 the IC was the longest railroad in the world. Its main line went from Cairo, Illinois, at the southern tip of the state, to Galena, in the northwest corner. A branch line went from Centralia, (named for the railroad) to the rapidly growing city of Chicago. In Chicago its tracks were laid along the shore of Lake Michigan and on an offshore causeway downtown, but land-filling and natural deposition have moved the present-day shore to the east.

In 1867 the Illinois Central extended its track into Iowa, and during the 1870s and 1880s the IC acquired and expanded railroads in the southern United States. IC lines crisscrossed the state of Mississippi and went as far as New Orleans, Louisiana, to the south and Louisville, Kentucky, in the east. In the 1880s, northern lines were built to Dodgeville, Wisconsin, Sioux Falls, South Dakota, and Omaha, Nebraska. Further expansion continued into the early twentieth century.

The Illinois Central, and the other "Harriman lines" owned by E.H. Harriman, was the target of the Illinois Central shopmen's strike of 1911. Although marked by violence and sabotage in the south, midwest, and western states, the strike was effectively over in a few months. The railroads simply hired replacements and withstood diminishing union pressure. The strike was eventually called off in 1915.