(With acknowledgment to the Trains Magazine Grain issue, April 2009.)
Until the late 1950s, all grain traffic traveled in temporarily-modified box cars, shipped in units of one between the local grain elevators, to be found typically within ten miles (and certainly within 25 miles) of every grain-shipping farm in North America, and their diverse destination at milling plants, terminal elevators at ports that exported the grain, or other diverse users. As unit lots, these box cars traveled in standard manifest trains following the normal routes of such trains between the origination and destination points for each car (except on the branch lines where their originating and/or destination points may have been). While the grain traffic represented perhaps the third heaviest traffic of the times, it was not normally represented as separate train flows in this time period.
By the 1990s, Unit Grain Trains represented one of the major freight flows in contemporary North American Railroading, not quite in the same league as intermodal and coal, but certainly in the top five. (Grain shipments falls into commodity groups that comprise 9% of total shipments and 13% of total revenue, between 2005 and 2007.) Depending on the size of a particular flow, unit trains may comprise "shuttles" of 110 cars, or smaller unit trains of 52 cars or 26 cars (perhaps combined with other such "units" for parts of their journey); historically, these have been developed from the smaller numbers of cars, growing to the larger numbers.
There are two major types of grains grown in North America: wheat and small grains (oats and barley), grown in North and South Dakota, Manitoba, Saskatchewan, and Alberta (durum and red spring wheat); Kansas, Oklahoma, southwestern Nebraska (red winter wheat); and parts of Washington, Idaho and Oregon (durum); and feed grains (corn, soybeans, and sorghum), grown in a belt from eastern Nebraska, eastern South Dakota, and northeastern Kansas, through southwestern Minnesota, Iowa, northern Missouri, Illinois, Indiana and southwestern Michigan to western Ohio. More than half of US corn production is used to feed animals, and moves from the corn belt to cattle feedlots in the southwest, poultry producers in the south, and dairy farms across the USA; about 20% is made into ethanol, while about 12% becomes food products, with 17% exported (mostly to Mexico).
BNSF hauls more grain than any other North American railroad. Former Great Northern and Northern Pacific lines in (mainly) North Dakota, along with Eastern Montana and far west Minnesota, serve many types of originating elevators in the wheat-growing areas. A relatively small number of these originating elevators comprise those contracted to provide the facilities needed for loading the 110-car "grain shuttles" that mainly run from the originating elevators to ports in the Pacific Northwest (primarily Portland, OR, but also Kalama, Tacoma and Seattle, WA), and feedlots at Plymouth, Attalia, Ritzville and Templin, WA, over the former GN Transcon, the former NP main line and the still-operating portion of the former Milwaukee Road (now owned by BNSF), east to Chicago and beyond on those same lines, and ports on the Gulf Coast, via various BNSF lines (see Other Routes, below) south to Sioux City and thence to Kansas City, taking the former Santa Fe route onwards to the Gulf Coast, as well as to large flour millers, such as those in the Twin Cities, also accessed over the former GN and former NP main lines, but heading east for these flows. Some grain also flows to Duluth/Superior for onward transport on the Great Lakes.
On the map on page 67 of the Trains Magazine Grain issue (April 2009), there appear to be 32 shuttle-capable elevators on BNSF lines, along with four more on 'captive' shortlines, for a total of 36 (with perhaps 18 more in the southern parts of South Dakota and Minnesota); 35 elevators capable of handling 50+ cars on BNSF lines, along with ten more on captive shortlines (45 total); and 17 elevators capable of handling 25-49 cars on BNSF lines (along with eleven more on captive shortlines (28 total).
There are eight shuttle-enable grain elevators on the former CB&Q Denver main line in southern Nebraska and southern Iowa, all of them in the corn belt. There are destination/combination shuttle-enabled elevators on this same line, westward towards Denver, serving feedlots as well as dry-farmers in the western portions of the wheat-growing area.
The former Santa Fe passenger main line in western Kansas lies in the Kansas-Oklahoma-Texas wheat belt, and has a number of shuttle-originating elevators located along it, at Coolidge, Garden City, Dodge City, Ensign (on a branch), Wright and the Hutchinson area. Two of these places (Garden City and Ensign) also have shuttle unloading facilities. The freight Transcon and its feeder lines has shuttle-originating elevators at Wichita (which also has shuttle unloading facilities) and Wellington.
The former Santa Fe main line from eastern Kansas through Kansas City to Chicago lies in the corn belt, and has a number of shuttle-originating elevators located along it, at Hardin, MO, and Ruff and Ransom, IL. Grain from the elevator at Ransom, IL, for example, takes shuttle trains to Texas or Mexico.
Most of the grain carried on the westerly portions of the former Santa Fe Transcon is feed-corn headed for feedlots in such places as the Amarillo to Clovis section of the Texas Panhandle (Amarillo, Hereford, Summerfield, and Friona, TX, and Clovis, NM), as well as Shattuck, OK, located right on the Transcon, and the Central Valley of California (Stockton, Hughson, Kings Park, Guernsey and Trigo), accessed via the Tehachapi route.
The routes from the wheat-growing areas to the Gulf Coast ports traverse areas roughly orthogonal to the traditional transcontinental main lines, and comprise lines from Willmar, MN, and Aberdeen, SD, south to Sioux City, IA, and thence to Kansas City, taking the former Santa Fe route onwards to the Gulf Coast, via Oklahoma City and Fort Worth. (Prior to the BNSF merger, in September, 1995, these trains would have taken the former Frisco south from Kansas City, via Tulsa and Fort Worth, and the former Burlington-Rock Island south of Fort Worth.)
The former Soo line branches, including those still run by CP and those now operated by shortlines, largely overlap those of the BNSF east of a line from Portal and Minot, ND, to Willmar, MN. In this area, there appear to be 17 shuttle-capable (100 cars on the CP) elevators on CP lines, along with ten more on captive shortlines (27 total); eleven elevators capable of handling 50+ cars on CP lines (and eleven more on captive shortlines), for a total of 22; and 5 elevators capable of handling 25-49 cars on CP lines (along with 17 more on captive shortlines), for another total of 22.
Soo-Line-originated grain shuttles use the UP Overland Route and Oregon Short Line to deliver grain to Pacific Northwest points.
The CP Main Line and its feeders between (roughly) Winnipeg and Calgary lie in the Canadian Wheat Belt. All wheat in Canada must, by law, be sold through the Canadian Wheat Board, which directs the destinations of shipments of wheat from the originating elevators along the main and feeder lines. CP operates grain trains to the ports of Vancouver, BC and Thunder Bay, ON (for onward shipment through the Great Lakes and St. Lawrence Seaway). In 2007, the number of grain elevators in the wheat belt of Canada was down from a peak of more than 5,700 elevators in more than 2,000 locations to just over 300 primary elevators in about 250 locations. Less than half of these would be on the CP.
The Iowa lines of the former Illinois Central, now owned by CN, lie in the northern reaches of the US corn belt. There are six CN-served shuttle-enabled originating grain elevators in Iowa. CN operates 100-car grain shuttles south along its former IC main line to the Gulf Coast ports along the Mississippi River west of New Orleans
The CN Main Lines and their feeders between (roughly) Winnipeg and Edmonton lie in the Canadian Wheat Belt. All wheat in Canada must, by law, be sold through the Canadian Wheat Board, which directs the destinations of shipments of wheat from the originating elevators along the main and feeder lines. CN operates 100-car shuttles from the Canadian prairies to the ports at Vancouver and Prince Rupert, BC, Thunder Bay, ON (for onward shipment through the Great Lakes and St. Lawrence Seaway), and (for a very few trains a year), Churchill, Manitoba. In 2007, the number of grain elevators in the wheat belt of Canada was down from a peak of more than 5,700 elevators in more than 2,000 locations to just over 300 primary elevators in about 250 locations, the majority of them on the CN.
The historic Overland Route, eastward from the middle of Nebraska to the fringes of Chicago, lies in the US corn belt. There are 41 UP-served shuttle-enabled originating grain elevators in Iowa and far southern Minnesota (and 21 more in Nebraska). UP can deliver this grain, as well as unit grain trains originating at points on the former Soo line, to Pacific Northwest ports, such as Portland, OR, (and Kalama, Tacoma, and Seattle, WA), or to feedlots, such as in Wallula, WA, Mountain Home, Bliss and Gooding, ID (and Burley, ID, on a branch), and Ogden, UT, using the Overland Route and its subsidiary lines (such as the Oregon Short Line). On the Salt Lake Route or its feeders, there are shuttle-unloading facilities at Nephi (on a branch) and Milford, UT
The California shuttle destinations at Stockton, Turlock, Delhi, Traver, Goshen, Tulare, Pixley and Famoso are all located on the former SP San Joaquin Valley line, accessible off the Overland Route or the Golden State Route.
Union Pacific's train symbols have separate symbols for Grain Empties, Grain Loads, Grain Dedicated and Grain Shuttle, thus providing for three classes of loaded grain train!
There are shuttle-originating elevators at Topeka, Hutchinson, Haviland, and Plains, KS, and Optima, OK, the latter also with shuttle-unloading facilities, on the former Rock Island section of the Golden State Route.
There are shuttle-destination elevators on the Sunset Route (which connects with the Golden State Route at El Paso) at Maricopa and Roll, AZ, and Calipatria (on a branch) and Kaiser, CA.
UP operates lines that reach from the corn belt south to the Gulf Coast ports along the Mississippi River west of New Orleans, and in the Beaumont, Galveston, and Houston areas of Texas. These include the directionally-operated former MoPac and former Cotton Belt lines, south from St. Louis through Texarkana, and the lines shared with unit coal trains south from Kansas City, through Fort Worth. Grain shuttles (75 cars or 100 cars on the UP) headed from the corn belt (or the wheat belt to the north of it) to those ports use these lines.
There are eleven CSX-affiliated shuttle-enabled originating grain elevators around the thumb in northeast Michigan, and at least one more elsewhere in Michigan (Newaygo). CSX operates 65-car and 90-car unit grain trains from these elevators to compliant unloading facilities, such as those on its lines in North Carolina (Shelby, Mount Olive, Rose Hill), South Carolina (Bascomville and Kershaw, both on a shortline), Georgia (Camilla (on a shortline), Valdosta, Brunswick), Florida (Lacoochee) and Alabama (Banks).
KCS operates 75-car and 110-car unit grain trains, southward from Kansas City, to destinations in Oklahoma (Broken Bow), Arkansas (Waldron), and Louisiana (Arcadia), as well as Gulf Ports.
Norfolk Southern operates 75-car unit trains of feed corn from the corn belt, through which its former Wabash lines run, to Southern feed mills, such as those on its lines in Georgia (Baldwin, Gainesville, Lavonia (on a shortline), Maysville, Rockmart, Forsyth, Surrency and Adel), North Carolina (Greensboro, Winston-Salem, Roaring River (on a shortline), and Raleigh), and South Carolina (Monetta).