Interurbans
What is an Interurban Railway?
An Interurban or Radial Railway is an electrically powered railway that operates in and between cities and towns. Interurbans often did not construct private right-of-way—instead, they would share tracks with streetcar lines in cities and steam-powered (or diesel in later years) freight lines in between. If an Interurban did purchase its own right-of-way it would most likely be aligned closely with major roads or other railways.
Interurban railroads first appeared in the late 1800s alongside major technological advancements, namely in electrical engineering. The advancements in electrical engineering allowed the invention of a major defining characteristic of an Interurban railway: electric traction. For electric traction to work, electricity is conducted through a suspended wire or third rail to power the motor of a train. Interurban railways thus required large amounts of electricity to operate. In many cases Interurban railways were bought or subsidized by electric companies. In Chicago, Samuel Insull, president of Commonwealth Edison, owned large portions of the major electric railways including: The Chicago North Shore & Milwaukee Railroad, The Chicago Aurora & Elgin Railroad, The Chicago South Shore & South Bend Railroad, and the Chicago Rapid Transit Company.
why interurbans?
In addition to the numerous technological changes that allowed the creation of Interurbans, across the United States and Canada, a great social change was occurring. People were rapidly moving from densely populated urban centers to suburbs. The pre-fabricated suburb that we are familiar with today (think McMansions) was not formally introduced until after the Second World War—the suburbs that spread across the United States in the early 20th century were more cosmopolitan. While the post-Second World War suburb promoted the automobile, the early 20th century suburb promoted train travel.
In Chicago, residents of the city proper were moving South, West, and North. Beginning in 1855 with the introduction of the Chicago & Milwaukee Railroad (Later the Chicago & Northwestern), all communities between Chicago and Waukegan were essentially founded as "bedroom communities." The Villages of Wilmette, Winnetka, Glencoe, and many others thrived because of the railroad. Many historians argue (and rightly so, I believe) that Chicago's North Shore only exists because of the influence of the railroad.
Some historians may be prompted to call Chicago's North Shore a collection of "streetcar suburbs," but I would argue that this is not the case. An better example of a "streetcar suburb," I think, would be Cudahy, Wisconsin, near Milwaukee. While the North Shore was served extensively by the C&ME and the CNS&M (Especially from the early 1900s - 1955), the communities within do not owe their existence to Interurbans—The Chicago and Milwaukee Railroad (Later the C&NW) is more directly responsible for their creation.
Heavy railways like the Chicago & Northwestern had limitations, though. Steam trains were very heavy and noisy—they required massive infrastructure like bridges and some smaller towns began to grow weary of the constant noise passing through their central business areas. Steam trains were also expensive to operate, so service was often more infrequent than was convenient. Even today's scheduled 1-train-an-hour is not terribly convenient. Lastly, steam trains were dangerous. They were so dangerous, in fact, that some municipalities along Chicago's North Shore chose to entirely regrade the tracks—in Evanston, the tracks were elevated; in Winnetka they were sunk.
The Interurban railway, on the other hand, was much more quite, much more frequent, and much safer. Interurbans could share infrastructure with preexisting railways (The North Shore Line shared trackage with the Northwestern Elevated, the CA&E shared trackage with the Metropolitan Garfield Park Branch, and the South Shore Line shared some trackage with the Illinois Central.) and run on roads like streetcars.
Evanston perhaps saw the largest change in settlement due to the railroads. In 1880, the population of Evanston was only 4,400. 20 years later, in 1900, the population had more than quadrupled to 19,259. On the left, I have superimposed two tiles from Sanborn Fire Insurance Maps. They are both the same exact area of Northwest Evanston only 30 years apart! In 1920 (seen in the map on the left side) the population of Evanston was 37,234. In 1950 (seen in the map on the right side) the population was 73,641.
Interestingly, (and perhaps not coincidentally) by the time that most land in Evanston was occupied, the North Shore Line was in dire straits. In 1955, 5 years after the publishing of the map on the right, the CNS&M's Shore Line route would cease operation.
(As a side note, notice the tracks of the North Shore & Western Railway on the very bottom of the 1920 map!)
The big three
The three largest and most well known Interurban railroads in Chicago were the Chicago, North Shore & Milwaukee Railroad, the Chicago, South Shore & South Bend Railroad, and the Chicago, Aurora & Elgin Railroad.
These three Interurbans are also the only three in the Chicago area that survived to see the collapse of the American Interurban Railway in the mid-to-late 1950s. The North Shore Line even surpassed the collapse and survived until 1963. The South Shore Line, amazingly, still exists today.