more crowded city center. Developers found they could increase profits by catering to this emerging group, shrinking lot sizes, and building more compact, less ornate houses. Initial development was divided into block lots and sold in 1852 with the condition that "substantial stone or brick buildings" be erected. The houses in this grouping are primarily three-story Italianate buildings, linked by material, decorative detail, and form. An additional but smaller and less ornate 16 Italianate, brownstone, semi-detached houses, similar in form to the initial houses, were built around Chester Avenue. The setback of these houses was 25 feet, allowing generous front yards. Another development on Locust Street, a project by banker and West Philly resident Clarence Howard Clark, comprised three-story, two-bay, brick, restrained Queen Anne rowhouses. The street was unified by front yards, and enclosed by decorative iron fences. The houses melded the suburban principles of front porches and greenspace with the urban rowhouse form, producing profitable, yet desirable, middle-class suburban housing. Other developments introduced urban density and architectural uniformity: the Queen Anne style with columned porches and decorative spindlework, brickwork and corbelling; steeply pitched gables with fishscale slate shingles; turrets; balconies; and windows with a single pane surrounded by small panes. These houses are typical of the early 20th-century developments in West Philadelphia, and are unified by rhythmic patterning of porch and gable features. The second story, projecting, semi-hexagonal bay is incorporated into this design, an element which defines the later rowhouses. The western reaches of West Philadelphia included miles of two-story rowhouses with bay windows above classical columned front porches. What resulted was a collection of Colonial Revival houses with Arts and Crafts influences, which reflect the sophisticated tastes of post-World War I Philadelphians. For the first time in West Philadelphia, houses had garages. Later Tudor and Spanish Revival houses, and the Art Deco influenced apartment houses also filled in available lot spaces between developments and made it possible for more middle-class Philadelphians to move to the area. Transportation Elevated Rail One of West Philadelphia's most prominent features is the "El", or SEPTA's Market-Frankford Line or Blue Line. Completed in 1907, this elevated subway line linked West Philadelphia, Millbourne and Upper Darby to Center City and then later to Frankford. Running above and, for a portion, under Market Street, this transportation link is one of Philadelphia's two major transit lines that transport hundreds of thousands of students and workers