When Did the Area Shaded Yellow Come into Existence in the American

When did the area shaded yellow come into existence in the American city?

A) the area in yellow is zoned for future urban growth in the 21st century
B) pre-1888, prior to the advent of streetcars
C) 1945 to present day, as freeways became a common urban feature
D) between 1888 and 1920 when streetcars were heavily used
E) 1920-1945 as the automobile became a common mode of transport