Herbert Clark Hoover, former President of the United States, died here yesterday at the age of 90. Death came at 11:35 A.M. in his suite on the 31st floor of the Waldorf Towers, following massive internal bleeding that began Saturday. His two sons were with him as he slipped into a deep coma that kept his final hours free of pain. Physicians and nurses had worked ceaselessly since he was stricken to prolong his final days. They arrested the bleeding in the upper intestinal tract and gave him frequent transfusions. But toxins poisoned his weakened system and, when bleeding recurred early yesterday, his heart could no longer take the strain. By 8 A.M., it was apparent that his illness was terminal, as a medical bulletin put it. Mr. Hoover, born in an Iowa village, the son of a Quaker blacksmith, was an exponent of a credo of personal initiative that he summed up as "rugged individualism," and his life exemplified it. His parents were poor and he was orphaned at 9, but he amassed a fortune as a mine engineer and owner. With the start of World War I, he directed the evacuation of 200,000 Americans from Europe. It was the first of a series of massive economic, evacuation and food relief activities that spanned half a century. He was Secretary of Commerce in the Administrations of Harding and Coolidge and was elected President on the Republican ticket in 1928. The crash of the stock market on Oct. 29, 1929, plunged the nation into its worst economic crisis in history. His policies were attacked as insufficient to spur economic revival. He was voted out of office in 1932 under the cloud of the Great Depression, called the "Hoover Depression" by his opponents. Some later judgments, however, have suggested that he was the victim of events that coincided with his tenure. And 30 years of public service, including tasks for two Presidents after he left the White House, restored him in the affections of millions. At news of Mr. Hoover's death, President Johnson proclaimed a 30-day mourning period and ordered the flags lowered to half-staff at the White House and on all Federal buildings and grounds in the nation, on Navy vessels at sea and at embassies and military stations abroad. At noon Sunday 21-gun salutes will be fired at military installations. When the flags are lowered at Retreat on Sunday, 50-gun rifle salutes will be fired. Mayor Wagner ordered flags lowered on all public buildings in the city for 30 days. Today and tomorrow from 9 A.M. to 3 P.M. the public will be admitted to the vast marble sanctuary of St. Bartholomew's Episcopal Church to file past Mr. Hoover's closed coffin. The church is on Park Avenue at 50th Street, across from the Waldorf's north entrance. Friday morning, the coffin will be moved to Washington in a railroad car. It will be carried by military escort to the Capital Rotunda, where the body will lie in state until Sunday morning. There the nation will pay its final honor to Mr. Hoover. The rotunda is the ceremonial center of state funerals. Abraham Lincoln was the first to lie there, in April, 1865. President Kennedy and Gen. Douglas MacArthur were the most recent. The only former President to rest there before Mr. Hoover was William Howard Taft. A memorial service, which President Johnson is scheduled to attend, will be conducted in St. Bartholomew's at 4:30 P.M. tomorrow by the Rev. Terance J. Finlay, the rector. It will not be open to the public. Mr. Finlay sometimes visited the former President in his suite. When Mrs. Hoover died, a similar, brief service was held for her in St. Bartholomew's. Mr. Hoover will be buried Sunday in West Branch, Iowa, the village where he was born. There will be a brief, simple ceremony called a Memorial Meeting for Worship, at the West Branch Conservative Meeting of the Society of Friends (Quakers), of which he was a lifetime member. His body will rest in a grave, the site of which he chose himself, on a grassy knoll overlooking the two-room cottage in which he was born on Aug. 10, 1874. Quakers do not hold religious "services," as such, but "meetings" marked by an absence of ritual. Therefore there will be only a brief graveside observance before the coffin is lowered into the earth. Mr. Hoover's wife, Lou Henry Hoover, who died in 1944 at the age of 70, is buried at Stanford University in California, which both attended and which is the site of the Hoover Institution on War, Revolution and Peace--but her body will be moved to the Iowa burial plot beside her husband's on the grounds of the Hoover's Library. Mr. Hoover was the 31st President of the United States by most reckonings, though some held him to be the 30th. Grover Cleveland, who served two nonconsecutive terms, was both the 22d and 24th President in the accounting that lists Mr. Hoover as the 31st occupant of the office. Mr. Hoover's death leaves the nation with two living former Presidents: Harry S. Truman, a Democrat, and Dwight D. Eisenhower, a Republican. Only one other President lived to be 90--John Adams, the second President, a Federalist, who was 90 years and 247 days old when he died on July 4, 1826 (the same day that Thomas Jefferson, the third President, died). Mr. Hoover was 90 years and 71 days old at death. Mr. Hoover's values were rooted in uncomplicated Quaker values of thrift, hard work and self- dependence, and he deplored a departure from those values in which he disparagingly termed "the century of the common man." He said the nation imperatively required "the leadership of the uncommon man or woman." And he cited his own life as proof of the validity of the American dream of achievement by effort, not grant. The first word of Mr. Hoover's death came in a terse, handwritten note on Waldorf stationery from his personal physician, Dr. Michael J. Lepore. It gave only name, date and time. Its text: "President Hoover. Oct. 20, 1964. Time: 11:35 A.M." Neil MacNeil, an old friend and associate of Mr. Hoover, immediately called a press conference on the fourth floor of the hotel. He asked for a glass of water before facing newsmen and cameras, and commented, "I'm undergoing a little shock today." Then, in a written statement, he declared: "A great American has ended a brilliant career of service to his fellow men. Above all, he was a humanitarian. He fed more people and saved more lives than any other man in history." A medical bulletin had been issued at 8:30 A.M., signaling the end. Noting that Mr. Hoover had lapsed into a coma, the bulletin said: "Early this morning, bleeding from the upper gastrointestinal tract recurred, placing an unbearable burden upon his already strained vascular system. His heart, which has borne up magnificently throughout the illness, has begun to fail and its rhythm has become totally irregular. "Renal [kidney] function is inadequate for the demands of his system and toxic products are accumulating in his blood stream. The emphasis in this terminal phase of his illness is upon keeping him comfortable and free of pain." Mr. Hoover's two sons, Allan Henry and Herbert Jr., had joined him Sunday, and both were in his suite at the time of death. Mr. Hoover also had six grandchildren. Mr. Hoover had suffered four serious illnesses in the last 26 months, and had been long confined to his suite, in which he kept six secretaries busy answering mail and compiling data for his many books, among other tasks. In 1960, he wrote 55,952 letters with his staff. He had become very hard of hearing lately, and aides and interviewers sometimes had to stand close and shout. "I'm used to being hollered at," he assured one visitor. His mind remained alert, and he maintained a steady interest in world affairs and sports until his final illness. He liked to reminisce about the old days, to watch football on color television and to read the newspapers or have them read to him. Mr. Hoover was 54 years old when he took the oath of office from Chief Justice William Howard Taft on March 4, 1929, with Calvin Coolidge, his immediate predecessor, at his side. He ran against Alfred E. Smith, the New York Governor who was called the Happy Warrior, and was elected with 21 million popular votes to Governor Smith's 15 million, and an electoral margin of 444 to 87. But four years later, with the nation in the grip of the Depression, with millions out of work and hundreds of thousands suffering cold and hunger and sometimes living in shantytowns called "Hoovervilles," Mr. Hoover ran against another New York Governor, Franklin D. Roosevelt, and was overwhelmed by a blizzard of 22.8 million votes for the Democrat. Mr. Hoover got 15.7 million votes and received 59 electoral votes to Mr. Roosevelt's 472. After his 1932 defeat, Mr. Hoover resumed his role as trustee of educational and scientific institutions, writer of books and articles and chairman of the Boys' Clubs of America. Under President Truman and President Eisenhower, he headed the Hoover Commission on the Organization of the Executive Branch of Government.