June 4, 2014: The national north end of US 77 is just across the border at I-29 in Sioux City.
Well, this is embarrassing: When I moved the website from mac.com, I moved the locations of the IA 12 South and US 77 pages. However, I never edited the links to those pages from the main IA 12 page. They are fixed now, and linked properly in this blog post.