The city of Chicago has a modest standard for parks: for every 1,000 people, there should be two acres of open space. Unfortunately, half of Chicago’s 2.7 million residents still live in communities that fail to meet that standard. Existing open spaces are often difficult to reach, due to highways and other arterial roadways blocking the way, or unsafe conditions caused by gang activity. Mayor Rahm Emanuel and the Chicago Park District have signaled their willingness to work on the problem, though much remains to be done.