The original Heritage Trail is about 25 miles of crushed limestone, but expansion projects have extended the start of the trail to the west of Beltline Rd by about .6 miles. There is no marker, but I have included a photograph. At 136, there is a shelter indicating the start of the Heritage Trail, even though there is no apparent trail. Just keep running down beltline road another half mile or so until the crushed limestone begins.
All construction/bridge work was complete at the time of this run (at least one of the bridges was out as of Thanksgiving 2019).
At the end of the crushed limestone path, continue running through the parking lot along the pond to find a blacktop path. Previous measurements of the trail end at 22nd and Elm in Dubuque (consistent with Google Maps and Google Maps Streetview). However, recent Bee Branch Creek development seems to have engulfed this portion of the Heritage Trail, extended an additional approximate half mile to 20th and Garfield.
No one ran with me for this run. All gels and hydration were carried in a race vest.