They say the best time to plant a tree was 20 years ago and the next best time is now.Great River Greening can celebrate having done both, and involving thousands of volunteers to get it done.So, Arbor Day, which is observed in Minnesota at the end of April, is an especially big day for us. Since we began in 1995, Great River Greening has hosted an Arbor Day event nearly every year, bringing a total of 4,300 families, colleagues, and friends out to plant trees on that day, rain or shine, though snow and hot spells.In 1997, 1,400 Xcel Energy (then NSP) employees and their families planted trees along a stretch of the Mississippi riverbank near downtown Saint Paul that has since matured in into a lush woodland.In just the past two years, 300 volunteers planted 4,500 saplings in the South Washington Conservation Corridor on Arbor Day, as part of an on-going effort to restore the area to an oak savanna.In the years between, volunteers have joined us on Arbor Day at sites throughout the Metro Area, working through frigid 20 degree mornings and unseasonably warm 80 degree days, creating beautiful natural spaces to return to enjoy year after year.Top picture, L-R clockwise : United Theological Seminary  (2007), South Washington Conservation Corridor  (2015) Longfellow-Shasta Restoration (2008), Cedar Creek Conservation Area  (2013),