In Indy, I-65 and 70 weren't completed until the late 70's, whereas I-465 was built first in the 60's and tagged onto I-65, 70 as well as I-69 outbound only. IIRC, as I was only a child myself, there was a lot of controversy as to getting the expressways into the city, people didn't want neighborhoods destroyed vs. Indiana's largest city and capitol not to be served by an interstate, least as I was told by my grandad, an Indiana native. That's why "as I understand it" I-74 got tagged on to I-465 as it really had no where to go. They(I-65/70) eventually got built, but took a while compared to other similar sized cities at the time, that already had expressways/interstates.