re: I-14 (14th Amendment HWY)—TX, LA, MS, AL, GA corridor—approved by US Senate

It’s a bit more complicated than that. Especially when considering control of access, interchanges, etc. This is why it could be 2-3 decades before large portions are even designated. I-69 and I-57 are current examples. While it’s a federal push, the states are going to make many of the choices within their boundaries.