In 1918 the General Assembly designated a 4002-mile (6441 km) state highway system to be maintained by the commission.

Beginning in 1922, the commission was authorized to add annually mileage equal to 2.5% of the original system (100 miles or 161 km).

However, Virginia's independent cities were excluded, typical of the Byrd Organization and its leader's rural priorities and political power base.

Generally, when an area became part of an independent city, through annexation, merger, consolidation, or conversions, the secondary roads passed from the state system to local responsibility.

This arrangement eventually led to new conflicts over ownership and responsibility for the circa 1928 Kings Highway Bridge across the Nansemond River on State Route 125, which was closed in 2005 by VDOT for safety reasons.