Course History info update:
From Coach Quick: From the Illinois site
Firstly, the IHSA has never admitted that the old Detweiller layout was short of 3.0 miles even though numerous people throughout its history have found it to be 2.97-2.99. Everyone always knew that the last mile was a bit short during the 1970s, 1980s, and 1990s. It is difficult to quantify for Virgin, Graves, Torres, or Sage how much faster this made their times. The IHSA will recognize Chris Derrick's recent run as the second fastest time ever. To them, the course lengths are identical now and then.
Secondly, the course as laid out now is three miles in length (with a small caveat you'll see later). They moved up the start line, changed the course right after the mile mark (you used to proceed on a diagonal to the back bridge), and the back loop. The course was surveyed by the Bradley University engineers and posts are driven into the ground at each 800 mark. These marks are used each year to set up the chip mats, start, finish, etc.
Third, the caveat. The new bridge that the runners take out of the back loop was not there until 2005, after they redid and surveyed the course. No one remarks about this, but it definitely cuts 10-15 meters off of the new course layout. Is that a huge deal? Not exactly, but the IHSA never really acknowledged the change. The bridges are side by side, but it does create a marginal difference.
Lastly, to those wondering about the splits, I think there are two factors involved. One, there are two long inclines in the third mile, which is the only mile where that occurs. Two, the little part I mentioned above about the new bridge is in the middle of the second mile.