Henry Deimel, a newlywed at 86, says the end stages of life are the best. Dapper in suit and checkered vest, he talks fondly of the Commerce and State Department posts that took him to New Delhi and Paris. But he does not long for the past. He and his wife Vivian have an active life at a retirement community at Thomas Circle -- though he has begun to worry that too many frail people are moving in.

Miriam Parker, 79, wears a white uniform as she works full time behind the pharmaceutical counter at the Kensington Pharmacy, which she and her late husband bought in 1949. Her son Richard, 57, teases about her inability to remember some obscure detail of his high school years -- "What, is your memory slipping?" -- but she dismisses him with a chuckle and a wave of the hand.

Esther Power, who preferred adventure to marriage, has had health problems but is still an independent soul. The 87-year-old Power is using her retirement years to dictate her memoirs, from her time at Oxford through her foreign language work for the government during World War II. She lives alone in a Georgetown efficiency.

Just a generation or two ago, Parker, Power and the Deimels would have been seen as exceptional -- middle-class people who had managed to stay active, alert and financially independent well past the traditional old-age marker of 65. But now this is the norm in the United States.

The current generation of elderly Americans is generally healthy, aided by significant gains in medical science and by government health care programs. Even most of the "oldest old" -- those 85 and above -- have no physical disabilities that limit their activities. Social Security and improved pensions are providing better retirement incomes than at any time in the past, and more than half of all Americans over the age of 65 own their homes outright.

And most older people are happy, according to a recent Washington Post poll of Washington area residents, with a plurality saying they are happier than when they were younger.

In some ways -- because of increased longevity -- problems such as frailty, poverty and loneliness have largely been pushed into the realm of the oldest old. Those over 65 now constitute about 12 percent of the population, and the numbers are expected to grow rapidly, but the fastest growing segment consists of those over 85 -- now just 1 percent of the population, but a group whose numbers are expected to triple over the next 35 years.

The irony for today's generation of elders was summed up by the staff director of the House Aging Committee, Fernando Torres-Gil:

"The aging of people in our society is a real success story. The good news is they are better educated, better off financially, having a good time. The bad news is they are living longer."

Of those over the age of 65 surveyed by The Post, 85 percent rated their health as good or excellent, and 86 percent said their financial plans have "worked out well," compared with 10 percent who said they have not. Chronic illness or incapacitation are the factors that most often exhaust savings and pension benefits, sometimes making paupers even of the well-to-do.

Good health and financial security mean independence for the elderly, which is clearly important to them: A large majority of those polled do not live with their children and of those an overwhelming 95 percent do not want to. The Retired Diplomat

Henry Deimel is in many ways typical of those who have retired from government careers here.

More than 30 years in government service did not make Deimel rich, but it did entitle him to a pension large enough to cover his needs as long as he is careful. He and his first wife Ruth had bought a house near American University for a low price and sold it for a "tremendous" one. As with many elderly, this windfall made a big difference in the money they had for retirement. They moved into an apartment at Thomas House, a complex for older people on Thomas Circle, where a meal and some cleaning and medical services are part of the bargain.

After Ruth's death, Henry Deimel met Vivian Cunningham, a widow who lived upstairs, and they "just clicked," he said. They married in May 1984, and now, says Vivian Deimel, "every day is Christmas."

Henry Deimel, one of 11 children, saw the vast changes of the 20th century from the varying vantage points of a boyhood in Europe with his father (a doctor turned underwear manufacturer), attending college in California, and serving in the departments of Commerce and State through the Great Depression and the Second World War. Retirement, he says, is better than all that.

"In general, it retirement is the most enjoyable period of my life," said Deimel in a diplomat's measured tones. "I'm my own man. I can do and think and say exactly as I choose . . . . I have learned so much more since I retired." The Deimels are involved in discussion groups that tackle such topics as European alliances and worldwide terrorism.

For Vivian Deimel, 79, a woman with an easy smile and gently curling gray hair, the decision to move to a complex in the middle of the city was made because "I wanted to be where the action is, not in a nursing home out in an old cornfield."

She has access to concerts and theater performances that she might not have elsewhere. But there is an overriding peace in knowing that her years as a visiting nurse and a bank teller here have lapsed into more enjoyable pursuits: "The greatest kick I get is getting a second cup of coffee, reading the paper and watching others go to work in the snow and rain, like I used to do." The Active Businesswoman

Miriam Parker at 79 embodies the falseness of the notion that aging has to mean slowing down physically and mentally. She works more than a full week, usually starting at 6:30 in the morning.

"I wouldn't give it up for anything, as long as my health stays good," Parker said of the family business.

Parker appears to be a living testimonial to the clean life: She says she does not drink, does not smoke, does not overeat and does not take pills except a calcium supplement.

Her husband died in 1964, and now her two sisters live with her in a small house in Kensington. Since none of them drives, they generally stay in at night, when Parker says she does the books for the pharmacy. As a hobby, she gardens.

The Parkers had four sons, two daughters, 27 grandchildren and 23 great-grandchildren. She said she can remember all the birthdays, as could her mother, who stayed active until three weeks before her death at the age of 94.

"I have a very busy life," Parker concluded. The Independent Scholar

For Esther Power, 87, the last few years have not been easy. But she has managed to stay independent and has enough money to support herself, despite having no family nearby.

Power had a stroke in 1979 and broke her hip in 1982, and she must use a wheelchair most of the time. Her eyes began deteriorating in the 1970s, and now she is nearly blind -- meaning that instead of writing her memoirs she is dictating them and getting editing help from a young woman who works at a local bookstore.

Power gets a pension of about $1,500 a month after working for the U.S. Signal Corps for 25 years until 1968 doing research involving foreign languages. The pension is enough for her necessities, she said, though nothing is left for luxuries.

"It takes all my money to have people serve me," said Power, sitting close to a window in her sunny Georgetown efficiency decorated with her own paintings. She pays a woman to clean and a nurse's aide to make supper. Local agencies such as the nonprofit Iona House, which serves older people in Northwest Washington, help with grocery shopping. Wearing a bright print dress and red canvas shoes, she says she has not been able to buy a new outfit since her hospitalization for the stroke in 1979.

Her retirement has been happy, she said, despite her problems.

"It's worked out all right. I don't mind," said Power, rolling gently back and forth in her wheelchair, looking through thick glasses. "I'm pretty independent, and I cope with things pretty well." The radio keeps her company at night, and she has "phone pals."

She cannot really explain why she never married, except that she could not accept a settled life: "I was an adventuress." An Improved Status

Much has changed during the lifetimes of today's elderly to make their situation better. Since 1930, average life expectancy at birth has increased by 13 years for men to 71 and by 17 years for women to 78.

Two-thirds of American workers now retire before the age of 65 and can expect 15 to 20 years in retirement, according to the Senate Aging Committee. In 1900, the average man spent 3 percent of his life in retirement; in 1980, he was spending 20 percent in retirement.

Social Security, now 50 years old, provides a base income and in 1980 surpassed earnings as the leading source of income nationally for families headed by someone over the age of 65. Pensions have improved as well, and they are the chief source of support for the elderly in the Washington area.

Poverty levels nationally and in this region have dropped dramatically for the elderly in the past 25 years. Figures in the District ran counter to that trend during the 1970s, however, with poverty rates in the city increasing.

Medicare, established 20 years ago as a federal health insurance program for those over 65, has paid for much of their health care. The Older Americans Act, also 20 years old, created more protections and services nationwide, such as delivered Meals on Wheels, nutrition centers and ombudsmen for those confined to a nursing home.

Only 5 percent of the country's elderly -- and even fewer in this area -- are in nursing homes, which are expensive and which many older people fear as a chilling last stop before the grave. Owning a Home

Some elderly are better off now because they were able to buy their own houses when they were younger -- a phenomenon aided by federal mortgage insurance started in the 1930s that let Americans buy over a longer period with a small down payment.

An example is Ernestine Hayes, who did not enter the world with many advantages. Her aging grandparents, former slaves, raised her after her parents separated, and "all they had to give me was love," said Hayes, now 73.

Hayes trained as a teacher, but after moving here from Youngstown, Ohio, in 1949, she became a beautician.

She bought her house on Swann Street NW in 1950 when whites were moving out, and she got it cheap, she said. Now it is filled with a large collection of plastic miniatures and flowers, bric-a-brac culled carefully from trips to flea markets.

She discovered at the age of 70 that she had an artistic talent -- and now the walls of her home are covered with her own oils, charcoals and pastels.

Her home, with a wild garden in back, is clearly a delight to Hayes, but it also is a key part of why she can make ends meet on her retirement income, without savings. She owns the house outright, meaning she does not have to worry about rent or mortgage bills. "I've managed fine," Hayes said.

"It's fun being old if you can get around," she said. This is much harder for her now, however, because she has been told that she has terminal lung cancer. Medicare and private insurance have kept her out-of-pocket costs for care within reason, she said.

Hayes, who has outlived two husbands, had two sons and a daughter. Her daughter moved back in with her recently, but Hayes vowed early in her illness to keep as independent as possible.

A doctor called last fall suggesting that she might want to be hospitalized for treatment, but she rejected the idea and would not be dissuaded. "It's my death," she told him firmly. A Story of Women

The story of aging is largely one of women, as they tend to outlive men. Most elderly men are married and living with their wives; most elderly women are widowed.

This is made vividly clear by a visit to nearly any facility for the elderly in the area, where men invariably are at a premium. At the dining room of a continuing care residence in Gaithersburg, a few neatly dressed men find themselves in a sea of women at dinnertime. At a retirement center in Virginia, an older woman trots closely behind a man using a walker, inching slowly to the clinic, and a nurse watching nearby explains: "Mrs. Jordan is trying to get a husband."

At the Hermitage, a retirement complex in Alexandria, marriage was a late-life venture for Muriel Coe, 72. She met Vance Cline, now 71, at the complex and married for the first time three years ago, after her retirement as a foreign shipping analyst for the U.S. Maritime Commission.

Vance Cline, a man of wry humor, had moved to the Hermitage with his first wife, who died suddenly. He and Muriel Coe started courting and one day quietly went out to be married.

On the register that staff members use to keep track of residents, the two signed out to go to Virginia Beach, Va., and wrote "Honeymoon" -- the only announcement they made. Now they travel a good deal and come back to their hobbies of bird watching, gardening and making wind chimes.

They are are among the youngest at the complex, an apartment building and nursing center near Shirley Highway that offers all levels of support services and care to residents, whose average age is 84. Coe said there is one drawback: "If you're a little younger, they get you for all the committees." "Medicare Row"

Washington's suburbs are graying rapidly, but the highest concentration of elderly in this area remains in the District, where 12 percent of the population is over 65 -- including a generation of civil service workers who came here during World War II.

Upper Connecticut Avenue -- lined with well-preserved buildings from other eras -- has become "Medicare Row," in the words of one older resident.

Elderly District residents can take the bus to any of a number of groups formed for active older people. One is a luncheon club at St. Margaret's Episcopal Church near Dupont Circle, where seniors get companionship over a hot lunch served for $1.

In the group on a recent afternoon was Lucius Thalley, 72, who retired as a GS 4 after working 30 years at the library of the Federal Reserve. A North Carolina native who came to Washington in 1934, he also has worked part time at an apartment building for 52 years and is now a switchboard operator there.

Thalley, a stocky man with a quick smile, said he keeps active despite a heart attack in 1982. He can make do on his civil service pension and Social Security, though he cannot afford to travel. He does regret not having a mate, however.

"Eventually, everyone gets lonely," he said. "I think it's meant for two. That's the only spot missing."

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