World War I changed transportation in Canada forever. Before 1914, the horse was still the primary means of moving people and goods. Steam railways were used for long hauls and to carry heavy freight, and electric railways or radial lines were expanding as a passenger and freight network.

However, the war effort relied on truck transport so much that after 1918, motorized vehicles quickly increased in popularity. Regional bus companies known as “rubber wheel” transport began to replace short-haul radial and railway service, and most plans for expanded radial networks were abandoned. In 1920, in response to growing demands to improve the provincial highway system, a Royal Commission investigated the increasing automobile and truck traffic.

Five years later, the construction of Highway 7 reached Markham Village. Grace Anglican church, which had faced Main Street, was moved and turned south to face the north side of the new highway. Because many properties could not be purchased or taken over by the province until the early 1930s, the highway did not completely pass through the region until that time.

Highway 7 is among Ontario's most important routes, particularly through Eastern Ontario where it is the only major through route north of Highway 401. At its peak, Highway 7 measured a total distance of 716 km in length. Starting in the 1990s, sections of Highway 7 were “downloaded” by the province to local municipalities. Although the opening of the toll Highway 407 parallel to Highway 7 has removed much of the through traffic, Highway 7 is still an important corridor to the City of Markham. In 2005, Highway 7 was made the second main artery for York Region's VIVA rapid transit service.