The end of the 2012 race calendar in Vicksburg will mark the start of a new era.

The 24th annual Over the River Run, a 5-mile run and racewalk across the Old Mississippi River Bridge scheduled for Saturday, is the last race of the year in the city and first of the new three-race Vicksburg Slam series.

The Slam offers cash prizes to runners and walkers who finish first overall and in their age groups at the Over the River Run, Chill in the Hills and Run Thru History.

Over the River Run race director Annette Kirklin said interest in the Slam, as well as a good weather forecast and a program geared toward getting children involved in the event’s 1-mile fun run, have sparked record registration numbers.

More than 600 people have registered for the OTRR, a number that’s expected to climb throughout the week. In 2011, a total of 733 people registered and 601 completed the OTRR’s three events.