October 25, 1893 - The Northwestern Elevated Railroad Company is incorporated. Though not one of its incorporators, its principal backer is traction magnate Charles Tyson Yerkes.
January 4, 1894 - As Mayor John P. Hopkins had refused to pass the original franchise ordinance (calling it too vague), another one is passed by the city council, but refused by the mayor. Less then a week later they tried again and were successful. The 50-year franchise stipulates that service must begin by January 1,1897 in order for the agreement to stay valid.
January 23, 1896 - The first steel of the "L" structure is erected at Fullerton and Sheffield Avenues. Later in the year, despite optimistic forecasts, it's determined that the Northwestern can not be ready for operations by the end of the year, so, at the Northwestern's request, the city counsel pushes the deadline for beginning service to December 31, 1897.
Late-November, 1897 - The structure stretches from Dayton Avenue (near the intersection of Halsted Street and North Avenue) to Buena Avenue. Work is suspended due to financial problems. Another extension is granted, pushing to deadline to January 1, 1899.
December, 1898 - With new money raised, construction crews resume work on the line, but with the January 1, 1899 deadline now impossible, the aldermen agree to give the company until December 31, 1899 to begin service.
Mid-May, 1899 - Most of the steel between Montrose Avenue and Halsted Street (about half the total distance) is in place. The aldermen reject the Northwestern's request for a time extension.
December 25, 1899, 3:55pm - The last span is put into place. Only one track is completed between Wilson Avenue and Kinzie Street and work on all but a few stations has not even been started. All efforts are directed towards having at least one track and a few stations completed so that token service could be operated to keep the franchise valid.
December 30, 1899, 2:13pm - The first train operated on the Northwestern, leaving the partially completed Wrightwood station bound for the Loop.
January 1, 1900 - Despite the service (albeit token service) in place, the Chicago Public Works commissioner declares the Northwestern's structure incomplete and unsafe, thereby nullifying the franchise. He orders the Northwestern to cease operations immediately.
January 2, 1900 - A train leaves Wilson Avenue in defiance of the commissioner's order. Four policemen board at Wrightwood Avenue and place the crew under arrest.
January 3, 1900 - The aldermen agree to give the Northwestern one more extension; this time until May 31, 1900. They make it clear that there will be no more extensions.
May 31, 1900 - The Northwestern reopens for service. The stations, north from the Loop, include Kinzie, Chicago, Division, Schiller, Sedgwick, Larrabee, Halsted, Center (later Armitage), Webster, Fullerton, Wrightwood, Diversey, Wellington, Belmont, Clark, Addison, Grace, Sheridan, Buena Park and Wilson. Stations at Willow and Oak would be added later. The four track structure includes express and local trains, with expresses stopping only at Wilson, Sheridan, Belmont, Fullerton, Halsted, Sedgwick, Kinzie and the Loop. The Northwestern begins operation with wooden trailers and motors using electric traction.
September, 1900 - Expresses no longer stop at Halsted or Sedgwick.
May, 1903 - A franchise is presented to the city counsel to build an extension of the Northwestern's tracks to serve the Ravenswood neighborhood. In light of the counsel's poor relationship with the Northwestern concerning franchises, they were in no hurry to approve it.
1904 - The Northwestern Elevated and the Chicago, Milwaukee & St. Paul Railway reach an agreement allowing rapid transit to come to Evanston, via the St. Paul's tracks into the suburb (the two lines meet at Wilson Avenue). Franchise problems stall an official agreement for another three years.
January, 1905 - The city council approves the Ravenswood franchise.
1906 - The Northwestern contracts with L.E. Meyers Co. to build the elevated structure between Clark Street (where it leaves the mainline) and Campbell Avenue (just beyond Western Avenue), as well as a surface extension to the terminal at Kimball and Lawrence Avenues.
March, 1907 - The Evanston City Council approves the electrification of the St. Paul's tracks from Howard Street to University Place, provided they are elevated by 1910.
March 5, 1907 - To relieve congestion, a new "lower Wilson Avenue" station and a loop track are built and put into service, with express trains routed to it.
May 18, 1907 - Ravenswood service is inaugurated to Western Avenue.
July 1, 1907 - Chicago follows Evanston's lead, authorizing electrification of the St. Paul's tracks from Graceland Avenue (later Irving Park Road) to Howard, but does not require the tracks to be elevated. A city ordinance did, however, prohibit the use of a third rail on surface-level tracks (even though it was used in just such a situation elsewhere in the city). As part of the agreement, the Northwestern had to provide 24-hour service to the Loop from all St. Paul stops, plus Hayes (later Loyola) and Howard. In exchange, the city would waive payment of a penalty owed by the Northwestern for not reaching the city limit by 1903, as per their original franchise.
December 14, 1907 - Ravenswood service is extended to the Kimball terminal.
May 16, 1908 - Service is extended north to Central Street in Evanston, using trackage owned by Chicago Milwaukee and St. Paul Railway. CM&StP had previously operated steam powered commuter trains over this line, and continued to operate freight service. The line remained at ground level, and was electrified with overhead trolley wire.
July 17, 1908 - The Chicago City Council approves the Northwestern's request for construction of a stub terminal at North Water Street and Clark Street, just outside the loop, to handle overflow rush hour traffic.
August 23, 1908 -Howard Avenue (later Howard Street) station opens, late due to construction delays.
Late-October, 1908 -Construction of an elevated embankment begins in Evanston.
November 17, 1908 -The North Water Street stub terminal opens to passengers. Many trains are rerouted there to alleviate Loop congestion.
January 6, 1909 - Foster Street station in Evanston opens, also late due to construction delays.
March, 1909 - Rush hour express service is instituted between Kimball and the Loop.
1910 - Evanston's track elevation is completed.
Summer, 1911 - The first consolidation of Chicago's rapid transit system takes place. The city's four "L" companies (the South Side Elevated Railroad, the Metropolitan West Side Elevated Railroad, the Chicago & Oak Park Elevated Railway and the Northwestern) form a "voluntary association" under the name of the Chicago Elevated Railways Collateral Trust (CER). The CER functioned as a holding company; yielding the benefits of centralized control without dissolving the underlying companies.
August, 1911 -The organizational structures of the four "L" companies are overhauled. Samuel Insull is elected as the CER's chairman, while Metropolitan Elevated's president Britton I. Budd is named president of the newly-formed CER.
February, 1912 - Northwestern Elevated President Britton I. Budd notifies Wilmette officials of his intention to construct a terminal and yard at Linden Avenue and 4th Street. Opposition develops, as Budd refuses an absurd franchise proposal from Wilmette officials.
April 1, 1912 - Under cover of night, a construction crew closes Laurel Avenue in Wilmette and constructs a half-car long platform a short spur track just south of Linden and about 150 feet east of 4th. Wilmette awakes to find itself with rapid transit to Chicago and, despite fears, becomes quite popular. The platform is lengthened later that year, plus a second track and temporary yard are added.
November 3, 1913 - Crosstown "L" service is first initiated, with trains running from Linden Avenue in Wilmette to the Stony Island Avenue terminal in Chicago's Jackson Park. The South Side and Northwestern trains operate on the outer track in a counterclockwise direction (actually only running over two sides of the Loop on each crosstown trip). Crosstown pairings include Evanston-Jackson Park, Wilson-Englewood, and Wilson-South Park runs (the last being believed to be very short-lived).
November 8, 1913 - A new, permanent station is added at Linden.
April 22, 1914 - Work on the elevation of the tracks between Lawrence Avenue and Howard Street begins. The elevation of the 4.5 mile segment, which was mandated by the 1907 ordinance, is expected to be a three year, $3 million effort.
August, 1914 - Work on the Lawrence-Howard elevation ceases due to financial problems.
1915 - Work on the Lawrence-Howard elevation resumes. The Thorndale Avenue station is added.
January, 1916 - Trains on the Lawrence-Howard stretch are moved onto a temporary wooden trestle, allowing the demolition of the original tracks and stations. Construction of the permanent embankment is slowed due to manpower and material shortages caused by World War I.
1918 - Edgewater Beach station (later changed to Berwyn Avenue) is opened.
August 6, 1919 - Chicago North Shore & Milwaukee Railroad interurban trains begin using line into downtown Chicago.
March 31, 1919 - The Chicago, North Shore & Milwaukee Railroad, Chicago, Milwaukee & St. Paul Railway and the CER execute a series of agreement giving the North Shore Line access to Chicago and the Loop via the Northwestern's tracks.
August 6, 1919 - The North Shore Line begins Chicago operations, with most trains terminating at Roosevelt Road (though the line's company office was at 209 S. Wabash, directly opposite the Adams & Wabash "L" stop). From 1922 to 1938, North Shore trains would terminate at the Dorchester Avenue station on the Jackson Park branch.
1920 - The Evanston City Council orders the elevation of the tracks from University Place in Evanston to Isabella Street on the Evanston-Wilmette border. Financing difficulties stall the project for eight years.
1921 - The Linden station is added onto. New "wings" on both sides give it a distinct Prairie School design. The Kinzie Street station is closed and demolished following the opening of a new Grand Avenue station a few blocks north. Elevation of the Lawrence-Howard section is virtually complete. A permanent northbound express track (the outer track on the east side) and permanent stations are yet to be completed. New station houses, built under the viaduct, are completed.
1922 - The new elevated four track main line between Lawrence and Howard is complete.
February 27, 1923 - The new station at Lawrence Avenue opens. Later in the year, a new, larger station is constructed at Wilson and the old terminal and yard are removed.