Sunday is only the fourth time the Sioux Falls Marathon has been run, but already the event is becoming a national player.

MarathonGuide.com ranks the Sioux Falls event as one of the best in the nation for qualifying runners for the Boston Marathon - more than 20% of last year's field in Sioux Falls ran fast enough to make it into the select field in Boston.

Wes Hall, of the Sioux Falls Sports Authority, says that kind of recognition is helping to grow the race (which has averaged about 290 runners in the first three years) to record shattering numbers in 2013:

Time is the key because there are qualifying times participants must reach, based on age, to get even have a chance to run in Boston, where the number of runners is capped each year, unlike other big races.

Check the latest Boston Marathon qualifying times here.

The key is the Sioux Falls marathon's route.  The 26.2-mile event is being run on a USA Track & Field (USATF) certified course with a total elevation change of 194 feet and a net elevation loss of 18 feet. Translation: it's flat by marathon course standards.

Getting the certification is the key, although it's not easy:

This year's marathon route begins at Howard Wood Field at 6:45am and finishes near Sertoma Park at 49th & Oxbow.

See the entire route here

Even if you're not running, there are several great places to catch a glimpse of the field as it passes by:

The half marathon is also expecting a much bigger turnout this year, with 1,400 - 1,500 runners taking part in the event, which starts at Howard Wood Field at 7:30am, finishing near Sertoma Park.

See the half marathon route

The other event Sunday is the Miracle 5K, at 8:30am, which starts and finishes at Sanford Wellness Center at 49th and Oxbow.