In just the last 50 years, Maryland has lost 500,000 acres of forest (along with 873,000 acres of farmland). As forests and farms are replaced and fragmented by subdivisions and shopping malls, Marylanders — already living in the country's fifth most densely populated state — lose more than just open space. The average state resident now has one of the longest commutes in the country. Water pollution, caused in part by failing suburban septic systems and runoff from roads and parking lots, gushes into the Chesapeake. Bird, bee and butterfly populations, stripped of food sources and breeding grounds, continue to crash. Air pollution, and the asthma that inevitably goes with it, gets worse without a cleansing tree cover.