It looks like a plain old road to strangers: the shops and filling stations, the edges of communities filled with small ramblers and large split-level houses and, at the road's end, the industrial parks, home to international corporations, with such street names as Forbes Boulevard and buildings of glass that glitter like new money.

But those who live and work along Martin Luther King Jr. Highway in Prince George's County look at the same road and see a thoroughfare that was once railroad tracks, then a dirt road, then a paved two-lane street and now a highway with four lanes. They see shops, once owned by whites, now owned by blacks, and neighborhoods where blacks from the District moved so they could buy their first homes.

They look at the green road signs that announce "Martin Luther King Jr. Highway" and see in them evidence of growing political clout. To them, that stretch of pavement, given King's name just two years ago, is a symbol of all that has changed in the two decades since his death.

It was a black state senator who led the successful move to have the 7.6-mile road, which runs southwest to northeast through the hearts of a string of black communities, renamed for the civil rights leader whose birth will be observed in a federal holiday tomorrow.

"Twenty years ago, when Martin Luther King died, there was one black elected {state} official from Prince George's County," said Sen. Decatur W. Trotter (D-Prince George's), who at the request of the county chapter of the Southern Christian Leadership Conference set in motion the process for renaming Rte. 704.

"We have a senator and three members of the House of Delegates and two {county} council members from this area now," Trotter said. "We have several judges on the Circuit Court level and District Court level. Blacks have added significantly to the boards and county councils.

"Years ago, the renaming would have been next to impossible to achieve," Trotter said. "But the fact that we have political clout now and people in leadership positions who understand the need to embellish and cultivate the past heritage helped us get that name changed."

For more than 40 years, the street was known as George Palmer Highway, the name a posthumous tribute to a white banker active in county politics and a leader in the fight to have the road built. Now, in addition to the name change, a $200,000 beautification project is scheduled to begin on the highway this spring.

Initially there were some objections to the renaming, mostly from business owners along the highway.

Raymond Smith, a longtime resident of Glenarden, would have preferred to rename Rte. 202. "Rt. 202 is a main road and it goes through both black and white neighborhoods," said Smith. "But the white businessmen refused. We already have a Martin Luther King playground in Glenarden. I didn't think renaming the highway would help.

"It was the way it was done which I objected to," said Smith. "It has significance now that it is done."

But most people, though they sometimes refer to the highway by its old name, have gladly accepted the new name.

"We felt the community was predominantly black and that our black youngsters . . . should be reminded of their black ethnicity . . . their heroes, and that they should have the name of someone they could relate to all year and not at just one time during the year," said Trotter, who moved from the District to Glenarden in 1958.

"I can assure you driving along that highway now is a very emotional feeling for me, especially when I'm returning home late from legislative sessions and I'm alone in the car," said Trotter, the head of the Legislative Black Caucus. "I am sure there are many others who feel the same."

Kevin Jefferson, a 28-year-old law clerk at a Landover firm and one of a younger breed of black political aspirants, calls driving along the renamed road "sheer joy. If you're into Martin Luther King and what he stands for, there is no way you can drive down that highway without feeling good."

Mary Seaward, part owner with her husband of Seaward Unisex Salon in Seat Pleasant, admitted that she still slips and calls the road by its old name. But, Seaward said, "Having the street named Martin Luther King Jr. Highway makes a lot of difference. I think about him every time I hear myself say that and every time I write the address.

"First I feel good, then I get sad thinking about the fact that he is no longer here," said Seaward, sitting behind the receptionist's desk at her shop at 5930 Martin Luther King Jr. Highway.

"I'm glad they decided to rename an important route after him, though," she said. "This is a way to constantly remember him, and he is a man you should never forget."

One of the blacks who moved from the District in search of an affordable home to buy, Seaward has lived in Seat Pleasant for 20 years. She reared her three children "in a nice, quiet neighborhood," she said, adding, "Most of the people on my block are still there."

Martin Luther King Jr. Highway starts at the District-Maryland line, an area peppered with small stores, barbershops, beauty salons, filling stations, a couple of churches, some boarded-up houses and "Sister Rita's" house of palmistry.

One of the first black-owned businesses in the area was The Seat Pleasant Barber Shop, where senior citizens get a break on the cost of a simple haircut and gossip is repeated over background music from a floor model 1940s Grundig-Majestic radio.

"We opened a day after Labor Day 1966," said coowner Edward L. Harrison, who lives in Glenarden, a few miles north up the highway. "I brought most of my customers with me from the District because there weren't too many blacks living out here. It has changed quite a bit on this road, especially when it comes to blacks owning businesses."

There are also a few Asian-owned businesses now -- stores once white-owned, then black-owned and now the domain of these recent immigrants.

Retail space on the highway is reasonable enough to offer a place where novice entrepreneurs can play out their dreams and new businesses can be tested.

The old Safeway and the A&P on the highway closed a couple of years ago. But Safeway recently opened a larger, more modern store just miles from the former location, and there is still an A&P nearby on Rte. 202, just an exit away from the earlier site.

The old A&P building has been remodeled and now houses several businesses -- a Trak Auto, an MLK Cleaners. A woman inside the cleaners said the business had been open a year.

The old Safeway is boarded up. In the parking lot, a sign has been posted in the dirt, proclaiming, "Coming Soon. 8,000 square feet of retail and office space." The sign stands next to the Norgetown 24-hour Laundry, where families march out with bulging bags of clean clothes.

Frank J. Blackwell, the mayor of Seat Pleasant, who has seen three decades of change, welcomes more. He has seen the population of his town go from 80 percent white, when he moved there in 1963, to 85 percent black today.

"I'm the third black mayor," Blackwell said. "Since the last election in 1984, the council has been 100 percent black. As more blacks have moved into the area, we've played a stronger role in the political arena. I think it sort of makes us proud to know we have a main highway through our town named after a great black American. It keeps alive the image and goals of his life."

Northeast along the highway, out of the retail strip of Seat Pleasant, past a community of brick attached houses, past the McDonald's built a year before King's death, through rural-like land, where trees haven't fallen to development, there is on a steep hill a set of renovated town houses and condominiums, where black children play on new yards, unaware that two decades ago members of their race were not allowed to live in those houses.

"Blacks couldn't live there, so they picketed the place. I guess the owners saw they couldn't keep blacks out because the next thing I knew, blacks were moving in there," recalled Helen Brown, who 20 years ago moved from the District to Palmer Park, a neighborhood named for George Palmer but made famous because former middle-weight boxing champion Sugar Ray Leonard grew up there.

Her neighborhood of duplexes backs up to the newly renovated town houses. "When I moved out here to Palmer Park, there were a lot of whites here," Brown said. "Everybody got along good in this community. There are still two white families living near me.

"The first whites were renters, then the blacks came and bought the houses and fixed the properties up real nice," she said. "A lot of people from the District were moving to the suburbs back then. The main thing was to own a house."

Smith remembers more about the highway than a lot of other people because he didn't move from the District.

He was born in Glenarden 69 years ago, and he has stayed there because it is a safe haven from crime, a pleasant community of mostly middle-class single-family detached houses.

Although some garden apartments have recently been the scene of drug-related violence, the disturbances have not spilled over into the neighborhood of well-kept yards.

For two decades, Smith has owned Smith's Barber Shop. His memory stretches back to a time when Martin Luther King Jr. Highway was "part of Washington, Baltimore and Annapolis railroad. A local train came every hour and children could ride to Washington for 12 cents," he said.

"This has always been a black community and it's always been one of the most progressive in some ways," Smith said. "We always worked together."

The Glenarden in which he grew up was home to women who did housekeeping for white families and men who worked on white-owned farms or did odd jobs. The town was filled with old houses, some with no indoor plumbing. But the urban renewal programs upgraded houses, Glenarden Woods was built, a section of split-level houses -- Fox Ridge, with lots as large as a half acre -- was established, and Smith watched his customers change.

"Kids grew up and came back with their kids," he said. "I've cut the hair of three or four generations. I was telling a guy the other day that I've seen kids who've come up under the welfare system and become successful professionals."

Although her family never lived on welfare, Patricia Gomez is a good example of how the labor of one generation in a family has boosted the quality of life for another. Her family moved to Glenarden in 1959 and she was among the first students to integrate county public schools in the mid-'60s.

She, her husband and two children live in Mitchellville, in a new community off Martin Luther King Jr. Highway, just a few miles northeast of her parents' home.

"Their house was a small rambler, a cinderblock constructed house in which they added on a family room," she said of her parents' house. "But moving to Glenarden was a step up for them. They moved there from a one-bedroom apartment where they lived with three children. I live in a split-level that's brick and aluminum. Basically, I always remember that because my parents worked to be able to afford an education for me, I'm able to do the things I do now."