Equity in transportation already had been a hot-button issue in Baltimore for years, including along Pulaski Highway.

In 1961, as President John F. Kennedy's administration struggled with how best to open the nation's transportation system to blacks, Maryland's roadways became a symbol of the obstacles.

Both Life and Time magazines ran stories about diplomats from newly independent African countries taking U.S. 40 from Washington to the United Nations in New York and complaining to the State Department after being turned away by local diner and motel owners.

The State Department dispatched its assistant chief of protocol to try to talk to the business owners. In a Time article from Oct. 13, 1961, the "beefy, red-faced" owner of a local restaurant is quoted as telling the State Department employee, "The hell with the United Nations and the hell with your colored diplomats!"

The incidents led to an apology from Gov. J. Millard Tawes, and, in 1963, Maryland passed a public accommodations law that banned segregation at roadside establishments, predating the nationwide Civil Rights Act of 1964.

When I-95 opened, it alleviated some of the remaining racial tensions on Pulaski Highway simply by offering an alternative route for black travelers, historians and local residents say.

It also immediately began turning rural enclaves into suburban commuter hubs while contributing to the steady exodus from city neighborhoods.

Between 1960 and 2010, as Baltimore's population shrank from 939,000 to 621,000, according to U.S. census data, formerly rural communities along the I-95 corridor saw spikes in population. Harford County, for instance, went from 77,000 residents in 1960 to more than 245,000 in 2010.

"I-95 made Harford County a bedroom community, because then you could jump on 95 and be in Baltimore in 20 minutes," said Anderson, 82, who served as Harford's county executive in the 1970s.

He welcomed the highway at the time, he said, but other motel and restaurant owners along Pulaski Highway were livid.

"You know how somebody says, 'We're going to build something,' and then you have 8,000 people against it no matter how good it is?'" Anderson said. "That's what you had with Interstate 95."

The business owners were smart to worry.

Before I-95, Pulaski Highway bustled with commerce and cars. Trucks rolled endlessly through town, and their drivers constituted the majority of business for some establishments, Anderson said.

"You could see everything God ever made going up and down that road," he said. "This was like a bustling, busy, busy operation, and then when [I-95] hit, that was the end of it."

Many of the hotels and restaurants went out of business or were forced to move closer to an I-95 exit, Anderson said.

As traffic on Pulaski Highway dropped off, it rose on the interstate. According to the Maryland Transportation Authority, the number of vehicles traveling through the state's Perryville toll plaza went from 6.2 million in 1964 to 29.2 million in fiscal year 2013.

Traveling on I-95 has become such an afterthought for East Coast residents that they sometimes forget its ubiquity in their lives, Zeller said.

"It's both mundane — all of us have driven there — but at the same time it ties into a lot of stories that we tell about ourselves," he said. "If you're born after 1960, then that's what you grow up with, that's ... the normal way of doing things."

Ruth Elliott, 78, a lifelong Aberdeen resident and current city councilwoman, said the highway allowed many in the town to have a suburban lifestyle for the first time.

Many residents were happy the I-95 corridor narrowly avoided their town and left its historical character intact when it was built, she said. But they were also thankful for the ease it brought to commuting to Baltimore and other nearby job markets.