followed along the Pennypack and Frankford Creeks, and traces of the mill races and dams remain to this day. The most famous of these factories was the Disston Saw Works in Tacony, founded by English industrialist Henry Disston, whose saw blades were world-renowned. Consolidation and population increase By 1854, Philadelphia County was incorporated into the city. In spite of the political incorporation, the Northeast retained its old development patterns for a time, and the dense populations and urban style of housing that marked older, more traditional sections of the city had not yet found their way there. In the first three decades of the 20th century, rapid industrialization led to the growth of industrial sections of the northeast and the neighborhoods surrounding them. These demographic changes, along with the building of the Market-Frankford Line train and new arterial highways, such as the Roosevelt Boulevard, brought new middle class populations to the lower half of the Northeast. Vast tracts of row homes were built in that section of the Northeast for new arrivals in the 1920s and 1930s, typically with small, but valued front lawns, which impart a "garden suburb" quality to much of the Northeast, reducing the sense of physical density felt elsewhere in the city. Much of this development occurred east of Roosevelt Boulevard (Mayfair, Torresdale) and in Oxford Circle. Post-war growth After World War II, newer arrivals, armed with the mortgage benefits of the GI Bill, brought the baby boom to the Northeast. This newer population was heavily Jewish or ethnic Catholic (including Irish, Italian, Polish, and German Americans) and completed the development of the region, filling in undeveloped areas of Rhawnhurst and Bell's Corner and developing the previously rural Far Northeast. As older sections of the city lost populations of young families, the Northeast's school-age population swelled, requiring rapid expansion of schools, libraries, cinemas, shopping, transportation, restaurants and other needed amenities. The period from 1945 through the 1970s was marked in many American cities by urban decline in older, more industrial areas. This was especially true in Philadelphia, in which much of the city's North, West and South sections lost population, factories, jobs and commerce. During the postwar period, the Northeast experienced a heavy influx of growing middle-class families, and had become an almost exclusively white community. This aroused controversy in the 1960s and 1970s, as passions for and against school busing were focused on the Northeast,