Highway 5 (Traditional Chinese: 國道5號), or The Alphabet Trail, is a precursor to the modern day Highway 505, and has once stretched from Archemedes to Topsity - Zephyr through what was Alphabet County. Today, a short stub of Highway 5 still exists in Downtown Archemedes as Alexander Street, signed as Highway 5. The stub runs from the Byte Roundabout to just west of Dixie Station, where it becomes an expressway leading into the City of Borden.
Highway 5 has existed as a road since Alphabet County was created. In the 1600s, the Alphabet Religion Activists began to set out west from the City of Borden, then the biggest city in the area, to spread their religion to the aboriginals living in the west side of the continent. These activists travelled for more than 500 km and they had set up settlements, or parishes, every 10 km to promote their religion. The path that was made became a vital route to link all these parishes and the only major cities at that time, Archemedes and Borden.
In the early 1700s, the path was cleared and widened into a proper road. Though not paved, it was heavily used by travellers and missionaries to travel between parishes. In 1810, the Alphabet County government was created, and one of the initial projects of the government was to pave the road, along with constructing the Golden Corridor Line as an alternate form of transportation to the road. The entire length of the road finished paving in January 1837, and was renamed "Alphabet Road".
In 1921, as an initiative to boost the economy after the world war, Alphabet County implemented a series of infrastructure project, including upgrading the entire length of Alphabet Road to become an at-grade highway. The highway was never completed since the emigre movement was ongoing, and the county has insufficient funds to continue the project. The highway only managed to be upgraded in sections, mostly in urban areas. The highway was renamed in 1932 as the "Alphabet Thruway" and signed as Highway 5 the same year, despite parts of the road remain unpaved.
In mid-1900s, Alphabet County dissolved into Gravenhurst Region. At this time, many of the settlement in the former county has been abandoned due to the emigre movement. The government of Gravenhurst Region planned to re-vitalize and re-populate the settlements across the Alphabet Belt, and began a project in the 1970s boom time to expand the highway. The highway was upgraded full-length to become a full-fledged four-laned expressway, and was opened to traffic on June 4, 1979. The new expressway was signed as Highway 505. The majority of the old alignment of Highway 5 was over-built with Highway 505 in rural areas, while in urban areas, rebuilding Highway 5 was impossible. As a result, short stubs of Highway 5 still exist (like in Archemedes) still managed by the regional government, and also exist as decommissioned sections as well. The decommissioned sections often run alongside Highway 505 as a service road, and renamed as either "Service Road" or "Old Highway 5".