What is the origin of highway numbering?

The numbering system for Dutch highways originated from early 20th-century plans to connect major cities. Initially, the lowest numbers were assigned to routes radiating from Amsterdam. The first highway, Rijksweg 12, opened in 1937, predating the A1. Over time, many planned routes were altered or never built, leading to discrepancies in numbering. For instance, the A3 was never completed, and the A18 now lies in a different region than originally intended. The original numbering scheme has largely been abandoned, with many numbers reassigned to newly constructed roads. Despite the A2 often being referred to as the oldest highway, it was not the first to open.