The history of Tampa Bay interstates is complex.
First there was I-4. As it grew during the 1960s it eventually ran from St Petersburg across the State.
Then I-75 came down from the north and, over time, ended in the place we call the Downtown interchange.
Over time, the Pinellas County portion of I-4 and the northern Tampa part of I-75 were renamed I-275 and a new I-75, then I-75E was created to be the Tampa by-pass route.
Each interstate had its own numbering system and was based on the sequential numbering of exits. For example, a vehicle entering Florida from Georgia would find the first exit to be No. 87.
There were 87 total exits on I-75 in Florida. Numbering started in Miami. Exit 87 was the last one before entering Georgia.
As Tampa's Interstate System continued to grow and highways were renamed, there was a need for a new system of labeling.
A national system was adopted using the mile marker or mile post. Using the earlier example, the old exit 87 became exit 467. It is 467 miles from the start of I-75 to the last exit in the state.
FDOT spokesperson Kris Carson said safety was the primary reason why the exits were renumbered in 2002.
"We did that for safety reasons, so emergency personnel would be able to get to people quicker and know exactly where people are from the mileposts," she said.
In 2002, there were still maps in circulation with the old numbers, so the state left the old number on the signs. As various construction projects have started since then, the old exit number signs have been removed.
Today, there are only a few left attached to overhead signs. They too will eventually become extinct.
Recently, the state also removed the old call-boxes from the interstate. Most drivers carry mobile devices, and therefore were no longer using the call-box.
The state is currently doing an inventory of any remaining old exit number signs and developing a plan to have them removed.