61) The earlier type of suburb, which was most dependent on the railroad, had a special advantage that could be fully appreciated only after it had disappeared. These suburbs, spread out along a railroad line, were discontinuous and properly spaced; and without the aid of legislation (法规) they were limited in population as well as area; for the biggest rarely held as many as ten thousand people, and under five thousand was more usual. In 1950, for example, Bronxville, New York, a typical upper-class suburb, had 6,778 people, while Riverside, Illinois, founded as early as 1869, had only 9,153.
62) The size and scale of the suburb, that of a neighborhood unit, was not entirely the result of its open planning, which favored low densities. Being served by a fail road line, with station stops from three to five miles apart, there was a natural limit to the spread of any particular community. 63) House had to be sited "within easy walking distance of the railroad station," as some old residents would point out; and only those wealthy enough to afford a horse and a carriage dared to penetrate farther into the open country.
64) Through its spaced station stops, the railroad suburb was at first kept from spreading or excessively increasing in numbers, for a natural greenbelt, often still under cultivation as park, gardens, remained between the suburbs and increased the available recreation area. Occasionally, in a few happy areas like Westchester, between 1915 and 1935 a parkway, like the Bronx River parkway, accompanied by continuous strip of park for pedestrian use, not yet overrun by a constant stream of urban traffic, added to the perfection of the whole suburban pattern. 65) Whatever one might say of the social disadvantages this was in many ways a perfect physical environment. But it lasted less than a generation.