The Retro River Run 5K is a run to celebrate the 40th anniversary of the Gate River Run. It is on March 4, one week before the city’s premier 15K race. The Retro River Run is open to just 2,204 participants, which is the number of people who ran the very first River Run. The cost to enter is just five bucks, which was the standard entry fee in the late 1970s. The race begins at 6 p.m. and starts and ends at the Jacksonville Landing. In addition to the run, there will be a 70s-costume contest and the oldest River Run t-shirt contest. Runners can register at www.1stplacesports.com/retro.html.