Everyone knows the ‘Blue Route.’ But what about the other colors?

Many Philadelphia residents have called I-476 the “Blue Route” for as long as they can remember.

The color in its name came from the colored pencils planners used to sketch out various possible paths for a new highway that would finally link the western suburbs to the Pennsylvania Turnpike, according to a 1991 Inquirer article.

But what were the other colors of the proposed highways? One reader asked this through Curious Philly, a forum where The Inquirer attempts to answer your most pressing questions about the region.

Planning for I-476 began after President Dwight D. Eisenhower founded the Interstate Highway System and signed the Federal-Aid Highway Act into law in 1956.

By mid-1956, engineers came up with three possible routes for Philly’s suburban highway connection: the Blue Route (the selected route), the Green Route (west of the Blue Route), and the Red Route (east of the Blue Route).

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The Green Route would have built the highway to wrap around just west of Media, said Brad Rudolph, a PennDot spokesperson.

According to a 1958 map, the Green Route would have diverged west from the current Blue Route in Radnor and rejoined right before the highway ended at the I-95 interchange.

The Red Route, also known as the Yellow Route, would have taken largely the same path as the Blue Route but extend slightly east starting in Marple and then run parallel to the current path.

While the two colors are often used interchangeably, they refer to two different proposals. The Red Route would have ended slightly west of the Yellow Route and been slightly cheaper to build, but it would have also displaced the most residents, according to a map in a 1976 Inquirer article.

The Pennsylvania Department of Highways — PennDot’s predecessor — initially recommended the Red (Yellow) Route in 1957 but was met with strong opposition.

The planners at the Department of Highways then revisited the alternatives in the coming years and ultimately decided on the Blue Route because it would serve the most drivers while also having a relatively smaller impact on communities with its construction, said Chuck Davies, the assistant district executive for design in PennDot’s Engineering District 6, which contains Philadelphia and neighboring counties.

He said the land that the Green Route passed through at the time was not as developed as it is today, making it less expensive to build but less appealing to drivers.

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The Blue Route generated controversy after it was first proposed as well, according to an Inquirer article from February 1957.

Homeowners as well as both Bryn Mawr College and Swarthmore College opposed the Blue Route. Civic groups advocated for the highway to be built further west than the Green Route, starting at the Pennsylvania Turnpike in Tredyffrin.

This would mark the beginning of a decades-long saga of controversy and construction before finally opening to drivers in 1992 in its current, complete form.

The selected path for the southernmost section of the I-476 also conveniently came with a catchy nickname.

It’s much easier to say “Blue Route” than its actual name, Davies said. (Its two official names are Mid-County Expressway and Veterans Memorial Highway.)

A former Delaware County planner who worked on the I-476 plans in the 1950s also said it was “easy to say” in a 1991 Inquirer article investigating the origins of the nickname.

“Blue just stuck,” Rudolph said. “No one says Mid-County Expressway.”

The Blue Route made it significantly easier to travel through eastern Pennsylvania. An average of about 80,000 to 100,000 drivers use the highway every day.

But the convenience came with a cost. An article from The Inquirer in 2011 said “It’s become so essential it’s often jammed itself.”

Rudolph said PennDot will experiment with flexible lanes and opening up additional lanes at peak times to ease traffic. The agency is also planning to repair bridges and repave large parts of the highway that run through Delaware and Montgomery Counties.