This is a callery pear, usually known as a Bradford pear. This is a non-native (Asian) invasive pest tree. Millions of them have escaped and taken over our park and natural areas. We recommend that you cut it down. They are not satisfactory landscape trees anyway, with lots of problems.
Here is more information about invasive plant in Maryland: http://extension.umd.edu/sites/default/files/_images/programs/hgic/Publications/not_updated/HG88%20I...