Complex sentence: Later numbered as Highway No.3, it was designated as a southern branch of the former Trans-Canada Highway by the 1920s and improved to gravel then eventually paved, widened with shoulders, and sections were upgraded to an expressway.
Split into simpler sentences: Later numbered as Highway 3, it was designated as a southern branch of the former Trans-Canada Highway by the 1920s. In subsequent decades, the dirt was improved to gravel then eventually paved, widened with shoulders, and sections were upgraded to an expressway.