 
		 
		 
		Drainage area plan, early 19th century
 
		Plan of Philadelphia, John Hills, 1796
 
		Ground Plan, Great Central Sanitary Fair, Philadelphia
 
		Drawing Dock Creek (2008)
 
		Plan of the City of Philadelphia and Adjoining Districts, 1830
 
		Map of Philadelphia showing Population in year 1920
 
		Map of the County of Philadelphia from Actual Survey, 1843
