So I am currently trying to make a region become fully interconnected with roads and make it like one big state/providence. I wonder if there is a mod out there that can make it easier to switch between the cities or keep the clock dependent to the region. For example: When I build up a small city, I go to another city, but it resets the clock back to 00 instead of 01. I think this would be really neat to see the game treat the region as one very large city if it's even possible.
There is no really need to change the date (I suppose that's what you meant with "clock"), but if you want to do this because it looks nicer, you can use a cheat code that is supplied with the Extra Cheats Plugin (https://community.simtropolis.com/files/file/21118-simcity-4-extra-cheats-plugin/). You can also change the in-game time, and even stop the clock (not sure if you need to do this everytime after loading a city, though).
While you could cheat the clock to make cities claim to be synchronized, the only way to run them alike is to visit each and crawl through time. BTW, cheetah speed sacrifices some parts of the model (like traffic path-finding), so unless you understand what's accelerated and what's ignored to make up for the acceleration, you should run on turtle speed (at least during the early days of rapid expansion).