Although these various circuits do not correspond in exact detail to one another, they may be said to be virtually superposed, and to serve not only the intensely active center of the city, but also the enclosing zone as far as the second boulevard circuit—Michigan Avenue, Twenty-second Street, Ashland Avenue, and Chicago Avenue—an ideal condition if the main circulation of the streets be left free and uninterrupted in its working. The center line on which balance the circuit A, and all the others to a greater or less degree, is the axial line of Congress Street. The two great arteries, Halsted and Congress streets, may be said to form the grand crossing, at the intersection of which it is proposed to place the civic center. The base of this civic center touches the west side of the inner circuit, tangent to which are all the other circuits. The importance of this inner circuit will thus be seen. The tangent or line of coincidence extends from Lake Street to Sixteenth Street. It may be used as the clearing-house for all the interests above described, coming to and going from the heart of the city. [Illustration: LXXIV. CHICAGO. DIAGRAM OF THE CITY CENTER, SHOWING THE GENERAL LOCATION OF EXISTING FREIGHT YARDS AND RAILROAD LINES, THE PRESENT TUNNEL SYSTEM AND PROPOSED CIRCUIT, AND CONNECTIONS FOR ALL THESE SERVICES, RUNNING TO THE CENTRAL CLEARING YARDS. COPYRIGHT, 1909, BY COMMERCIAL CLUB OF CHICAGO ] The passenger lines entering the densely inhabited parts of the city should not cross each other or carriage roads at grade. Much has been done already, and much more is proposed to eliminate grade crossings. In European cities, and in some American cities as well, the railroads have taken great pains to beautify their rights-of-way, a step very important to the roads themselves, to individual passengers, and to the community at large. Cleanliness and pleasing treatment of the roadways, the embankments, the drainage channels, the fences, the yards, and the stations, large and small, insure better service on the part of the railroad employees, while the appearance of the city is immensely improved thereby. [Illustration: LXXV. CHICAGO. DIAGRAM OF THE CITY, SHOWING COMPLETE SYSTEM OF INNER CIRCUITS. (1) General traction subway circuit. (2) General railroad freight circuit. COPYRIGHT, 1909, BY COMMERCIAL CLUB OF CHICAGO ]