The late 1930s and early 1940s saw the first manifestations of real crowd-control problems at Valley Forge, particularly in the spring, when the impressive concentration of flowering dogwood trees dedicated to Washington and his army drew almost a million visitors annually. A 1936 memo decreed: "We cannot allow visitors all the time they may desire. They must be satisfied with such view as they get moving along or else our physical task will be too difficult." 
How to deal with the hordes of visitors as well as people who wanted to locate permanently at Valley Forge became a key park issue between the 1950s and 1976 as the general area became increasingly developed. Concurrent bad press, financial problems, and trouble between the park commission and its parent organization caused individuals involved at Valley Forge and concerned members of the community to develop a kind of siege mentality. When the National Park Service took over Valley Forge on July 4, 1976, its uniformed rangers were welcomed like the cavalry arriving at a besieged frontier town.
An era of highway-building opened immediately after World War II, soon bringing a modern high-speed artery to the very edge of Valley Forge State Park. In 1944, land in Upper Merion Township was condemned to make way for the Pennsylvania Turnpike. A local editorial titled "A Threat to Hallowed Acres" acknowledged that highways were necessary but protested that "few persons are of the opinion that these adjuncts of the twentieth century should be permitted to disfigure those shrines which are a part of this nation's glorious past."  For almost a year, the park commissioners had been trying to second-guess what effect the turnpike would have on Valley Forge, but they made no official protest.  And indeed, other than making the park more easily reached by travelers from distant parts of the state, the new road brought no real changes to Valley Forge.
Change would come once the Schuylkill Expressway provided a high-speed route from the turnpike's Valley Forge exit directly to downtown Philadelphia. The expressway had evolved from plans for a "Valley Forge Parkway," proposed as early as 1930 to link Valley Forge and Fairmount Park.  After World War II, the expressway was again proposed as an alternative to widening existing roadways. Its planned route was to follow the Schuylkill River to Gulph Mills, where it would join a yet-to-be-built Route 202 near Valley Forge State Park. Construction began in 1950, and the Schuylkill Expressway officially opened in 1958. On the very first day, traffic became snarled, but the road system then in place made it inevitable that the village near Valley Forge with the peculiar name "King of Prussia" would become a major hub of commercial and industrial development, a kind of satellite community outside the city of Philadelphia.