CONTENTS THE AFFECTED ENVIRONMENT — 255 Context for Planning and Development of the National Mall ...................................................................257 1790–1850..................................................................................................................................................257 L’Enfant Plan....................................................................................................................................257 Changes on the National Mall .......................................................................................................258 1850–1900..................................................................................................................................................259 The Downing Plan...........................................................................................................................259 Changes on the National Mall .......................................................................................................259 1900–1950..................................................................................................................................................260 The McMillan Plan..........................................................................................................................260 Changes on the National Mall .......................................................................................................262 Federal Legislation and Administration.......................................................................................262 1950 to 2000 ..............................................................................................................................................262 Federal Plans ....................................................................................................................................262 Changes on the National Mall .......................................................................................................263 Federal Legislation ..........................................................................................................................264 Current Conditions — 2000 to 2010......................................................................................................264 Federal Plans ....................................................................................................................................264 Changes on the National Mall .......................................................................................................265 Federal Legislation ..........................................................................................................................265 Cultural Resources ...........................................................................................................................................266 Memorials .................................................................................................................................................266 Historic Districts ......................................................................................................................................266 The Mall............................................................................................................................................266 East and West Potomac Parks........................................................................................................272 Federal Triangle Historic District .................................................................................................272 Northwest Rectangle.......................................................................................................................272 Pennsylvania Avenue Historic District.........................................................................................272 Downtown Historic District ..........................................................................................................272 Historic Properties and Cultural Landscapes ......................................................................................273 The National Mall ...........................................................................................................................273 The Mall............................................................................................................................................276 Washington Monument and Grounds .........................................................................................283 West Potomac Park (North of Independence Avenue) .............................................................287 West Potomac Park (South of Independence Avenue) ..............................................................294 Roadways Contributing to National Register Listings........................................................................299 Natural Resources ............................................................................................................................................300 Water Resources.......................................................................................................................................300 Surface Water...................................................................................................................................300 Floodplains and Stormwaters ........................................................................................................302 Groundwater....................................................................................................................................303 Soils ............................................................................................................................................................303 Fill ...................................................................................................................................................303 Soil Conditions.................................................................................................................................304 Vegetation .................................................................................................................................................304 Elm Trees..........................................................................................................................................305 Cherry Trees.....................................................................................................................................305 Turfgrass ...........................................................................................................................................306 i CONTENTS Fish and Wildlife ......................................................................................................................................307 Demonstrations, Special Events, and National Celebrations .....................................................................309 Background Information ........................................................................................................................309 The Importance of the Venue........................................................................................................309 Regulations .......................................................................................................................................309 Number and Size of Events ............................................................................................................309 Time Frame ......................................................................................................................................312 First Amendment Activities ....................................................................................................................312 National Celebrations..............................................................................................................................319 Special Events ...........................................................................................................................................319 Access and Circulation.....................................................................................................................................323 Public Access.............................................................................................................................................323 Road Network..................................................................................................................................323 Visitor Access ...................................................................................................................................325 The Pedestrian Environment..................................................................................................................329 Bicycling ....................................................................................................................................................330 Visitor Experience ............................................................................................................................................331 Visitor Use Characteristics......................................................................................................................331 Visitor Profiles .................................................................................................................................332