Section 5-509 - Zoning districts for Baltimore-Washington International Thurgood Marshall Airport(a) In this section, "district" means the land area established for Baltimore-Washington International Thurgood Marshall Airport delineated by and contained within a circle the radius of which is 4 miles from a point the Maryland grid coordinates of which are E893,909.99 -- N490,279.30.(b)(1) Except as otherwise provided in this subtitle, a structure may not be erected, altered, or maintained and a tree or other vegetation may not be allowed to grow or be maintained at a height greater than the height limit established for the district.(2) The Administration shall adopt regulations establishing the maximum height limit any structure, tree, or other vegetation may be allowed to grow or be maintained in the district, consistent with applicable federal aviation regulations.(3) The Administration shall file in the land records of Anne Arundel County, Baltimore County, and Howard County a map depicting the district established by this section.