The Old Dinky Trolley Station at Big Bend Boulevard and Wydown Boulevard.

The platting of these subdivisions was possible because of improved transportation and the flight of upper and middle class residents from the city of St. Louis in the late 19th and early 20th Century. Though settlement in what is now Clayton occurred early in the 19th Century, it wasn't until 1876 that the community began to take shape. That year the "Great Divorce" separated the governments of St. Louis City and St. Louis County. The newly reorganized county platted their new county seat on 104 acres donated by Ralph Clayton and Martin Hanley in 1877. The new county seat, located conveniently on a rail line completed in 1872, drew the attention of wealthy St. Louis citizens who wanted to escape the pollution and congestion the City. This westward movement was boosted in 1892 by opening of trolley service to the area by the St. Louis and Suburban Railroad. The "Dinky" or "04" line traveled up present day Wydown Boulevard from Union Boulevard and Forest Park in St. Louis City. The line eventually extended to the St. Louis Country Club and past the John Burroughs High School, a private school in Ladue (western St. Louis County). The line allowed Clayton citizens to commute to work, their country club or to the elite private school. It also allowed residential succession to the more western county suburbs.

The eastern half of Clayton developed later than the central business district and its western subdivisions. The platting of the eastern subdivisions of Clayton, including the Hi-Pointe/De Mun Historic District and boundary increase, was influenced in large part by the challenge of commuting. It was much too far to walk to downtown Clayton to work and Forest Park proved a substantial barrier to commutes to downtown St. Louis without mass transportation systems. Until the mid-1980s when I-170 was opened, there was no easy way to travel north-south in the City or eastern part of the County of St. Louis. Major commuting arteries ran roughly west from downtown, which strongly influence urban-suburban residential succession patterns. (See Exhibit 10 for visual evidence that this pattern still exists three-quarters of a century later.)

The streetcar lines were in large part responsible for the expansion of suburban growth into the late nineteenth century. This growth exploded as the automobile grew in popularity by the 1920s. Access to these modes of transportation made it possible for people to escape cities for suburban living. Cities were increasingly becoming more crowded and congested and the rapid industrialization produced conditions that were frequently not healthy. The move to the suburbs was initially solely for the upper class. This can be seen in the development of Clayton's Brentmoor Park, three subdivisions designed by Henry Wright for some of the regions best known businessmen and members of elite of the city and county. However, with the growth of populism during the Progressive Era, the focus turned to providing better housing for all, including the working and upper-middle classes. The Hi-Pointe/De Mun Historic District and Boundary Increase provided housing tailored more restrictively to these classes than the surrounding subdivisions. These subdivisions were also designed to cater to the growing number of automobile commuters.