The orange line is the currently adopted route of the proposed 710 Freeway Extension. It takes nearly 1000 homes, clear-cuts 7000 trees, splits cohesive neighborhoods and guts 6 historic districts.

The yellow line is one of the prior routes that Caltrans preferred because it traversed mostly vacant land and therefore would be far less costly. South Pasadena agreed to this route because it didn't slice their city into 4 parts and it took vacant land (today this land is covered with homes built in the '70s). But South Pasadena was surrounded by larger more powerful jurisdictions, Los Angeles, Alhambra, and Pasadena. Certain elected officials in Los Angeles felt this route came too close to high-density residential developments planned on their side of the border. Pasadena redevelopment interests were keen on "creating a new large market area from the south", and conversely, Alhambra wanted a "new large market area from the North". Pasadena rightly did not want the freeway through Arroyo Seco parkland but preferred it to follow a soon to be abandoned rail right-of-way that abutted Fair Oaks Ave on it's west side. A large Pasadena institution was a key player in shoving the route west through the middle of historic Pasadena neighborhoods despite huge protests from residents.

Soon after, the National Environmental Quality Act and the California Environmental Quality Act were passed and South Pasadena, Sierra Club and a Pasadena grass-roots organization filed a lawsuit to force Caltrans to produce an EIR. A judge then filed an injunction until an EIR was approved which did not happen for another 25 years.