On September 1st, the construction of Mainline US 66 began. The road will connect the towns of Los Angeles, Central US, and Detroit (thanks to the US 66 E project which was finished on August 31st.)
Phase 1: California through the Rockies (9/1/2018-Present)
This phase will be the toughest phase as it runs from the eastern border of Los Angeles through the Rockies, possibly requiring tunnels. However, a path has been set out by markers which minimizes the amount of tunnels required.
Phase 2: Rockies to the Town of Central_US (not yet begun)
This phase should be very simple, as it's mostly flat ground.
Phase 3: Central_US to Chicago (not yet begun)
The final section of the real life US 66, this would normally be where the road ends. However;
Phase E: Chicago to Detroit (Finished!)
This is the only portion that will be maintained by the City of Detroit unless it expands to cover more.
All phases except for Phase E will be in the following pattern: 1 cobblestone block on each side of a line of Polished Diorite. A possible upgrade may be considered.