The 3M Half Marathon, now named the Austin International Half is an annual half marathon held in Austin, Texas, United States.

The 3M Half Marathon boasts one of the fastest 21.098 km (13.110 mi) courses in the country.

Runners enjoy a point-to-point course with mostly downhill running.

Starting in north Austin and finishing near the Texas State Capitol, the course has a net elevation drop of more than 300 feet.

As a result, the event has adapted the tagline “Downhill to Downtown.” Because the net elevation drop exceeds a ration of 1:1,000, times recorded in the race are ineligible for world record consideration and for entry standards in World Athletics events.