. . . every American mother believes her son will one day be president, but much as I love tradition and believe in perpetuating good ones, that is one to which I never subscribed. -- Sara Delano Roosevelt, 1933

HYDE PARK -- "The Champ," "The Sphinx," "That Man." They all are here and each one of them is Franklin Delano Roosevelt.

For a generation of Americans, now well-established in middle age and beyond, each of those political nicknames conjures up a different image. Roosevelt served as president longer than any other man, and his 100th birthday this month will begin a yearlong series of special events around a picturesque, tree-shrouded plateau overlooking the Hudson River.

In addition to the symposia and scholarly conferences scheduled throughout 1982 at Hyde Park, other activities marking the FDR Centennial are planned from Hawaii (he was the first president to visit the islands) to Nova Scotia (where he had a summer home), according to Peter Kovler, president of the Chicago-based FDR Centennial Committee. All told, these events will constitute the largest national observance of a historic milestone since the Bicentennial, Kovler said.

In Washington, the Smithsonian will mount a $200,000 FDR exhibit, concentrating on his precedent-setting work as a mass communicator. Part of the exhibit will be a re-creation (at the Museum of American History, beginning Jan. 30) of the White House broadcast studio from which he made his legendary fireside chats. The National Portrait Gallery, the National Air and Space Museum, the Museum of American Art, the Hirshhorn Museum and the National Archives all will have special exhibits dealing with the Roosevelt era, according to Kovler, 29, a writer whose family owns the Jim Beam distillery. Some have already opened, and an exhibit titled "Mary McLeod Bethune and Roosevelt's 'Black Cabinet' " will open today at the Anacostia Neighborhood Museum.

There will be birthday ceremonies and a special, yearlong exhibit at FDR's home in Warm Springs, Ga., where he went for treatment of his polio and where he died on April 12, 1945. A summertime celebration of the Roosevelt Centennial also is planned for Campobello Island, off Nova Scotia, where the summer home is now a museum.

Fund-raising events on behalf of the Democratic Party, and other special "FDR Day" observances, are planned for New York; Oakland, Calif.; Idaho and Hawaii, among other places, Kovler said.

Perhaps what would have pleased stamp collector FDR the most, however, will be the smallest item to mark his 100th birthday: The U.S. Postal Service will issue a new commemorative stamp in his honor on Jan. 30.

FDR was born on Jan. 30, 1882, in a second-floor bedroom of an old frame colonial mansion his father, James Roosevelt, purchased here in 1867 and called "Springwood." He was the only child of Sara Delano Roosevelt, a tall, formidable beauty who was 26 in October 1880, when she married the future president's father, a 52-year-old widower with a grown son her own age.

Modern visitors to the house, built around 1826 on a wide field surrounded by elms, maples, chestnuts and beeches, find a structure considerably different from the one in which FDR was born on a clear, frigid winter night a century ago. (The attending physician, a former Civil War surgeon, charged $50 for delivering what the proud father wrote was "a splendid large baby boy," weighing 10 pounds.)

Although the original building and rooms are intact, FDR and his mother -- still referred to as "Mrs. James" by the older townspeople in this small community just north of Poughkeepsie -- altered and expanded the residence in 1915. They had the white clapboards removed, resurfaced the walls with stucco and added a porch with a sweeping balustrade, giving the front a decided Georgian flavor. They also added a third floor and two fieldstone wings, one of which contains a high-ceilinged, oak-paneled living room and library with windows affording a magnificent view of the Hudson. In all, there are 35 rooms and nine baths.

The house has remained unchanged, however, since that alteration. Furnished largely with middle- to late-19th-century furniture that was old when FDR was young, it has a thoroughly "lived in" -- even dowdy -- appearance that somehow retains a glimmer of landed gentry elegance. It always was the place FDR considered home, despite the other residences, including New York City and Albany.

It was to this house that hordes of politicans (whom his mother detested) trooped to be consulted and courted; it was here that he awaited election returns, celebrated his four presidential victories with scrambled egg suppers and had a small office he dubbed the "Summer White House"; it was here that he welcomed world leaders, including the King and Queen of England during a memorable 1939 visit. And it is here, in an adjacent rose garden rimmed by tall hedges of hemlock, that he and Eleanor Roosevelt, his wife of 40 years, lie buried.

This house was not a particularly happy place for Eleanor Roosevelt, whose marriage to FDR, we now know, suffered severe strains. The home in Hyde Park was always the domain of her domineering mother-in-law, who lived to be 86 and died here in 1941. And FDR was romantically involved with one woman, and probably another, while married to Eleanor.

Yet it is the ghostly presence of his wife, always more of a guest and never mistress in this house, that greets visitors to the home today. By means of a spellbinding, 24-minute tour of the house she tape-recorded about six months before she died in 1962, Eleanor Roosevelt guides the visitor to the threshold of the main rooms on the first and second floors and gives a little talk on each, sprinkling her discourse with amusing, personal -- and sometimes revealing -- anecdotes.

In the living room, for example, one sees a large, life-size oil portrait of FDR painted in 1932 by Ellen Emmett Rand.

"My husband and I didn't like it," Eleanor Roosevelt confides, "but my mother-in-law did, so the artist gave it to her and it has been here ever since."

One is told that the "Dresden" sitting room, so named because of a Dresden chandelier and mantel set the president's father bought in Germany in 1866, was the elder Mrs. Roosevelt's favorite.

"But we never liked it because the chairs were uncomfortable," Eleanor says, again providing the kind of family tidbit not found on the plaques set on small stands before each room. She also recalls how King George VI remarked to an aide during his visit that none of his ministers had been as informative or candid as FDR in describing the international situation on the eve of World War II. This demonstrates, Eleanor observes, that "people who are in a position of being dependent on you, of course, are never quite as frank, never quite as able to tell exactly what they think" as those with no ax to grind.

Beeping tones on the tape cassette, which can be rented with an accompanying earplug at a cost of 79 cents for one person and $1.32 for two, advise the visitor when to turn off the tape in order to move from one point of interest to the next. At each stop on the tour, Mrs. Roosevelt comments on the significance of the room or part of the decor, such as FDR's large collection of stuffed birds in the main hall and a series of 18th- and 19th-century anti-British cartoons, which were left up during the king's visit, much to his amusement.

In the stone wing over the living room, visitors see FDR's bedroom, still cluttered with the books and magazines that were there when he last visited the house in March 1945. His favorite family photographs are on the walls, his improvised wheelchair and Navy cape are in an adjoining dressing room, and the chair in which his dog, Fala, slept sits at the foot of his bed. On the wall beside FDR's pillow is a telephone that once was a direct line to the White House.

There also are the guest rooms once occupied by Winston Churchill, Prime Minister Mackenzie King of Canada and the king and queen of England, as well as FDR's boyhood bedroom and the one in which he was born.

Eleanor Roosevelt's small, sparsely furnished bedroom is next to FDR's, in between her mother-in-law's and her husband's. She spent little time there, having had a cottage of her own built in 1926 on the eastern section of the sprawling 500-acre estate. It became her permanent residence following FDR's death, at which time she and her children surrendered all rights to the main house and grounds. The central 188-acre core of the estate now is under the care of the National Park Service of the federal Department of the Interior.

A short stroll from the house is the Franklin D. Roosevelt Library and Museum, designed by FDR and built of native Hudson Valley fieldstone.

Like so many enduring creations of his era (Social Security, banking and security reforms, the Tennessee Valley Authority), the concept of the presidential library is another legacy of FDR. There now are six others -- the Herbert Hoover in West Branch, Iowa; Harry Truman's in Independence, Mo.; the Dwight D. Eisenhower in Abilene, Kan.; John F. Kennedy's in Boston; the Lyndon B. Johnson in Austin, Tex., and the Gerald R. Ford Library in Ann Arbor and Museum in Grand Rapids, Mich. (The Jimmy Carter and Richard Nixon libraries are still in preparation.) These libraries not only concentrate and preserve the important historical documents that often were scattered and destroyed in earlier presidencies, but demonstrate that all historic sites in the United States aren't situated in Washington, D.C., or Virginia.

FDR appears to have thought of building a library to house his presidential papers and historical documents of the Hudson River Valley area as early as 1934, the second year of his first term in office. But he didn't draw up a rough sketch of the library until April 1937, and actual construction (undertaken by a private foundation) did not begin until 1939. The completed building was turned over to the federal government on July 4, 1940, and the museum opened on June 30, 1941.

Roosevelt did not conceive of the library and museum as the sort of "pyramid complex to massive egos" that some of the gargantuan edifices erected on behalf of his successors have been labeled, according to William Emerson, a military historian from Yale who has been the library's director since 1974.

The library is only 45,250 square feet in size, with just 15,000 square feet devoted to the museum. The rest is set aside as working space for the staff of 10 scholars and archivists, as well as 20 security and maintenance people. Thousands of scholars from around the country and the world have used its research facilities since 1946.

Rather than building a monument to himself, Roosevelt was interested in "educating the public about our Constitution and the role of the president in it," Emerson said. There is much in the modest museum to do just that. Photographs, historic documents and other memorabilia -- arranged chronologically and concentrating on the crucial developments of Roosevelt's unparalleled 12-year presidency -- graphically convey his awesome mastery of the job and his infectious joy in it.

In addition to the items dealing with Roosevelt's virtuoso handling of the four main roles assigned to every president -- party leader, head of government, head of state and commander-in-chief -- there are reminders of the reaction to his performance, which was both adulatory and outraged.

For example, there are two of the most famous cartoons of the Roosevelt era: a September 1939 New Yorker drawing by Peter Arno depicting a group of tuxedoed, newsreel-bound society swells urging their friends, "Come along. We're going to the Trans Lux to hiss Roosevelt"; and a November 1938 Esquire watercolor by Dorothy McKay showing a boy scrawling the name "Roosevelt" on the sidewalk while a small girl cries out: "Mother, Wilfred wrote a bad word!" (The latter was a favorite of FDR's and hung in his cabin at the Maryland mountain retreat he called "Shangri-La" and which President Eisenhower re-christened Camp David.)

Against a back wall looms perhaps the most striking caricature ever done of Roosevelt, a huge papier-ma che' bust of him as a jaunty, grinning sphinx, determinedly silent about his decision on whether to seek a third term. It was crafted by James D. Preston and presented to FDR at the December 1939 dinner of the Gridiron Club, an exclusive social organization of journalists.

The centerpiece of the exhibits in the main gallery is Roosevelt's White House desk and chair. The desk top overflows with a cheerfully jumbled assortment of some of the trinkets and souvenirs he enjoyed keeping on it, including a variety of Democratic donkeys and three or four of his famous cigarette holders.

The museum also contains many remnants of Roosevelt's multi-faceted interests. A compulsive collector, he specialized in naval prints, historic manuscripts, sheet music, miniature books, children's books, portraits of his presidential predecessors and, most of all, stamps. He began collecting stamps as a child (and designed a number of them as president) and his 150-album collection, auctioned at his request following his death in 1945, then was worth $228,000. Some of the collection since has been returned to the museum.

In addition, a separate wing of the museum, opened in 1972, is devoted to the life and work of Eleanor Roosevelt, whose independent accomplishments as a diplomat and human rights advocate earned her the appellation "First Lady of the World."

As part of the centenary ceremonies, a new room dedicated to the history of Dutchess County, N.Y., where Hyde Park is located, will be opened. Such a room was a "fond hope of FDR's, now being realized after 40 years," said. Emerson.

The library's research collection of documents totals more than 15 million papers and about 110,000 photographs. Intriguingly, only two or three photographs show Roosevelt in a wheelchair. His legs were permanently paralyzed by a polio attack in 1921, and he could move about only with the aid of a wheelchair or heavy steel braces and a cane.

Press photographers, displaying a gracious self-restraint not especially notable today, accepted an unspoken agreement never to photograph FDR being wheeled or carried. There is no newsreel footage of his laborious, painful -- and therefore inspiring -- approaches to the podium before a speech. Because he appeared so vigorous and healthy from the waist up, audiences witnessing his efforts for the first time often were stunned to see the extent of his disability.

A particularly fascinating reminder of that incapacity is Roosevelt's specially designed, hand-operated 1936 Ford Phaeton, which sits on the ground floor of the museum. He loved to drive the car, which has manual controls for the accelerator, brakes and gearshift, over the estate. He put 19,143 miles on it. (A somewhat blurred photograph shows him giving a worried-looking George VI a high-speed spin around the grounds.)

The Roosevelt home, museum and library are open from 9 to 5 every day of the year except Christmas and New Year's Day. The combined admission charge for both (as well as for the nearby Vanderbilt mansion) is $1.50, with senior citizens, Golden Eagle cardholders, visitors under 16 years of age and all school groups admitted free.

Hyde Park is about 85 miles north of Manhattan, exactly halfway between New York City and Albany. Travelers should take I684 north to 84 west, then take New York State Rte. 9 north at Fishkill, near Poughkeepsie, and watch for the signs to Hyde Park.

It is a pleasant, scenic drive through the rolling hills of the Hudson River Valley, and during the fall it is spectacular. It was an area FDR loved, but the affection often was not requited. He never carried Hyde Park, a staunch Republican community. The locals "approach FDR the way a thoroughbred horse owner would approach a horse he's very proud of but doesn't quite like,". Emerson said.

Like him or not, they know his memory is good for business. There were 316,535 visitors to the Roosevelt home and library in 1980, each bearing tourist dollars. A silhouette of FDR, his cigarette holder tilted skyward, is the emblem of the Hyde Park Chamber of Commerce.