President Dwight D. Eisenhower’s Federal-Aid Highway Act of 1956 built 41,000 miles of interconnected highways across the country. 
The bill arrived in an era of post-World War II, Cold War tension. Its proponents said highways were necessary for national defense. In case of an attack, people in densely populated cities would need roadways to evacuate. 
Across the country, highways were placed directly through towns, bisecting neighborhoods and changing the social fabric of communities. Some were routed through Black and minority neighborhoods that city leaders considered unsightly. 
"Urban renewal” programs sometimes used highways as barriers between Black and white parts of town.
In Phoenix, highway construction came years later than other big cities, and the pushback by residents was strong. Mostly middle- and upper-class white residents of Phoenix were able to bargain for alterations and accommodations when infrastructure came in. For mostly low-income Black and Latino neighborhoods, the result was different.