We are about 90 minutes from DC, 105 minutes from Philly, 200 minutes from New York, and 410 minutes from Boston. By far the closest airport is Baltimore Washington International (75 minutes away), but Reagan National in DC is less than 120 minutes away. The closest train stop is in Wilmington, Delaware, from which the drive to Chestertown is about an hour.
There is free street parking on the weekends. Additional (and free) public parking is right around the corner from Bookplate - turn left onto Cannon street and the lot is about 3/4 of the way down the block on the right. If those directions are too complex, you can get a map for that too, right here.