After 5 p.m., the block springs to life. People come home from their jobs, have dinner and sit on their front porches as the hot summer nights blend into the cooler fall. Children play on the sidewalks and ride bikes.

Some time at night, Mayor Walter Washington's chauffeur-driven limousine arrives and the mayor enters his gray, three-story brick home at 408 T St. N.W.

It is LeDroit Park, the mayor's neighborhood, and there are some people in the neighborhood whose only contact with Washington is a glimpse as he comes and goes about city business.

He waves and says hello to the neighbors he sees, but they never chat. He does not visit them, they say, nor do they visit him.

"I hardly know that he's there," said Martena Byrd, who has lived at the corner of Fifth and T Streets since 1917 and has a view of the mayor's home from her front porch.

"He's just another person to me," she said. "He has a job and he does it."

It's that job that keeps him out of the neighborhood so much, Mayor Washington said when asked about some of his neighbors' comments. "I'm away in the morning and I get back late at night. . . I'm out doing the city's business all day and half the night. You cannot stay at home with the city," he said.

"I would like to have more time to leisurely sit and visit friends but I don't have the time."

The neighbors sometimes complain of city services, but they don't like to take their problems directly to Washington's doorstep.

They seem to agree with Deborah Walker, who has lived directly across T Street from Washington for 12 years.

"If I had a problem, I wouldn't go there," she said, looking out her front window at the mayor's home. I'd probably go to his office. His home is not a place of business. That's where he comes to relax. For me to come over, that's no good for anybody."

Some people do come, Washington said. He has found citizens needing a place to live, or food or heat waiting for him on his front steps some evenings when he has returned home.

During the day the block has been practically deserted except for the policeman in front of the mayor's house. Only the block's several retired residents are at home and they stay inside.

The houses are as varied as their residents are alike. One or two are old Victorians. Others are large, semidetached brick homes. Some are nondescript brownish row brick and there is an apartment house on the corner.

The mayor's home belongs to his wife's family, the Bullocks, who moved there in 1918, when LeDroit Park was the prestigious address of the first families of black Washington.

The mayor's brother-in-law, William H. Bullock, maintains his doctor's office and residence there and the mayor's sister-in-law, Portia, lived there until her death last September.

LeDroit Park had been an all white neighborhood at the foot of Howard University until the turn of the century. Then, slowly, professional blacks and the educated black elite from Howard broke the color barrier.

"Al my teachers from Dunbar (High School) and Howard used to live here," recalled Etelka M. Randolph, who was born at 403 T St. NW.

The Bullocks belonged to this home-owning society. George O. Bullock, the mayor's father-in-law, was the minister of the Third Baptist Church for many years. Third Baptist is one of the largest and most influential black churches in the city.

After World War II, when blacks started to move to other neighborhoods, the professionals vanished.

Only the Bullocks and a few others stayed and watched the large three and four-story Victorian homes that distinguish LeDroit Park cut up into apartments and boarding houses for poor black families escaping from urban renewal in Southwest.

"I think it's a wonderful neighborhood but it's had its ups and downs." Washington said recently. "It has gone through a series of changes."

He said his family was the only one to stay as the neighborhood changed. "We thought it was important to stay because the neighborhood needed some strength," he said.

"Now it's starting to stabilize again," Washington said, because young people, including some whites, are again buying homes in the community and remodeling them.

LeDroit Park reflects its two histories. The well-kept semidetached homes along the 400 and 500 blocks of U and T streets recall the black bourgeoisie legacy, but the dilapidated houses that surround these streets symbolize the partial slum it has become.

Boarded-up houses blight the mayor's block and others, and there are stories of break-ins and muggings.

"It's pretty tough now," Mrs. Byrd said. "I'm afraid to go out my back door, that's why all these bars are up around here," she said, pointing to the iron bars that cover her first floor windows.

The bars went up after her home was burglarized a few years ago, she said.

A woman living across the street from Washington, who asked to remain anonymous, said that after two break-ins at her home she tore down her garage in the back of her home and her back porch to give her neighbors a greater opportunity of seeing any would-be burglars.

Crime decreased in the community during the first six months of this years, compared to the same period last year, police statistics report. From January to June 1977, there were 135 crimes and 80 this year in the same period.

The decrease included a decline in robberies from 30 to 12, burglaries from 28 to 22 and larcenies from 50 to 28.

Overall crime was reduced in the area by 40 percent, police said, adding that such a decrease was not unusual in a small community. Neither patrols nor surveillance have been increased in the neighborhood, they said.

Theressa Brown, president of the neighborhood preservation society, credits Washington's presence with helping LeDroit Park to gain its recent historic district designation, which officially recognizes the area's historical and architectural importance to the city and prevents buildings there from being torn down or changed without city review.

Mrs. Brown seldom talks to Washington about the neighborhood, she said, because she fears his intervention on behalf of the community might be construed by critics as showing favoritism.

"It's a very difficult position for him to be in, so I try not to bother him," she said. But she added, without his presence "we might have been ignored."