The popular midweek trail race series in the metro area is back May 25.

The Endless Summer Trail Run Series opens its four-race schedule with a 10-kilometer run at Lebanon Hills Regional Park in Eagan.

"We ask that everyone who comes and runs one of the Endless Summer Trail Run Series events introduces themselves to at least one new person during or after the race," said race director John Storkamp.

The remaining races, all on Wednesdays and all $25 apiece, are a 5K on June 15 at French Regional Park in Plymouth; a seven-miler July 13 at Lebanon; and a seven-miler Aug. 10 at Hyland Lake Park Reserve in Bloomington.

The series has garnered national attention as the best-organized, best-attended weekday trail run in the country. All of the races in the series, which is in its fourth year, sold out in advance last year. The field limit is 450 runners. Register online at estrs.com.