Running from April 1 to September 15, the Oak Leaf Discovery Tour (OLDT) encourages you to explore the 125-mile-long Oak Leaf Trail that winds its way through Milwaukee County. The Oak Leaf Trail is divided into nine lines, each running through various types of terrain and featuring unique points of interest. An important feature of the OLDT is a mobile “passport” app that helps you track the points of interest you see on the trail. Check off points of interest in the app as you experience them. Check off 10 or more points of interest, and you’re eligible to win prizes at the OLDT end-of-the-season party on Sunday, September 15. Special offers from Milwaukee area craft brewers and other local businesses are also offered in the app. Cost of the passport app: $5.