Irving Swanson liked to say that he led America’s entry into World War II and then brought the war to an end.

On Dec. 8, 1941, the day after the Japanese attack on Pearl Harbor, he was the 29-year-old congressional clerk who took the roll call when the U.S. House of Representatives voted to declare war. Minutes earlier, he was seated steps away from Franklin D. Roosevelt when the president gave his “day of infamy” speech before a joint session of Congress.

Three days later, Roosevelt did not come to Capitol Hill to deliver his call to arms against two other Axis powers, Germany and Italy. The task fell to Mr. Swanson.

“The forces endeavoring to enslave the entire world now are moving toward this hemisphere,” he read from Roosevelt’s message, the podium crowded with radio microphones.

Then, once again, the bespectacled Mr. Swanson called on the 435 House members for their votes, his deep baritone voice reverberating in the chamber.

U.S. Speaker of the House Sam Rayburn, rear, presides over the House of Representatives as Irving W. Swanson reads President Franklin D. Roosevelt's plea for a declaration of war against Germany in Washington, D.C. on Dec. 11, 1941. (AP1941/ASSOCIATED PRESS)

After the nation was at war for four years, Mr. Swanson was in the House to announce the peace. In 1945, he read into the Congressional Record the message of the Japanese surrender.

Mr. Swanson died Feb. 13 at his home in Rockville of complications from internal bleeding, his nephew Jonathan McMurray said. He was 99.

Capitol Hill still employs “reading clerks,” as Mr. Swanson’s job was known, to read aloud the resolutions being debated before the House and incoming communications from the Senate.

Since the 1970s, however, the task of taking the roll by voice, a sort of manual labor of democracy, has been replaced almost entirely by electronic voting. Only on rare occasions, such as the election of a speaker or the opening of a session of Congress, does the House return to the old tradition that Mr. Swanson carried out so many times.

As a young law student in 1940, he was working at what became the Congressional Research Service when he heard that the House needed someone to take over for a reading clerk who by then was in his 90s.

The interview process entailed an audition before Sam Rayburn of Texas, the newly elected Democratic speaker, along with Lewis Deschler, the House parliamentarian. After Mr. Swanson showed off his baritone voice, and after he told the two men that he had won a singing contest in high school, he was hired.

At that time, the House floor was a noisier place than it often is today — “bedlam,” as Mr. Swanson said in a 2004 interview with House historian Matthew Wasniewski. Attendance peaked in the summer, Mr. Swanson wryly noted, when the offices of the Capitol building were “hotter than the hinges of Hades” and House members poured into the air-conditioned chamber.

His voice rising over the din, Mr. Swanson would read the various resolutions that came before the House and then begin the roll.

“Mr. So-and-so,” he would call out, to which the member, if present, would respond. “Mr. So-and-so votes, ‘Aye,’ ” Mr. Swanson would repeat, as a tally clerk marked the vote. For every roll call vote, the process was repeated 435 times. As the minutes passed, the clamor would sometimes grow, and the speaker would bang the gavel for order.

But the day the House voted to declare war on Japan, “you could hear the drop of a pin,” Mr. Swanson said. “Easy to take the roll call, I can tell you. Everybody was quiet. Very serious.”

The most striking vote he recorded that day was that of Jeannette Rankin (R-Mont.). Rankin, the first woman elected to the House of Representatives, voted against the American entry into both world wars because she was a pacifist.

Under intense pressure, Rankin remained true to her convictions and voted “present” on the subsequent resolutions to declare war on Germany and Italy.

After the last name was called that day, Rayburn thanked Mr. Swanson for his stalwartness and presented him with a gift as a memento of those trying days. It was the speaker’s gavel.

Irving Wallace Swanson was born Feb. 25, 1912, in Hudson, Wis. He settled in Washington to study at George Washington University, where he received a bachelor of law degree in 1941.

During World War II, he served briefly in the Navy as a military liaison with congressional offices. Rayburn arranged for an early discharge, Mr. Swanson told the House historian, so that the young man could return to his job in the chamber.

In 1953, Mr. Swanson lost his job in the House amid controversy surrounding a kickback scheme that ended the career of Rep. Ernest Bramblett (R-Calif.), who had been accused of nepotism after hiring his wife as a secretary.

Mr. Swanson testified that he had helped arrange for his wife, the former Margaret McMurray, to appear on the payroll instead of the congressman’s wife, who continued working in the office. The money paid to Mr. Swanson’s wife was then turned over to Bramblett, who was convicted of falsifying his payroll.

Mr. Swanson was not prosecuted and was subsequently hired in the Senate, where he worked for the next decade and a half as a special assistant to the Republican majority and minority secretaries. He also worked for the Republican senatorial campaign committee, then headed by Sen. Barry Goldwater of Arizona.

Mr. Swanson left the government in 1967 and became legislative counsel to pharmaceutical and technology companies before retiring in the 1980s.

His wife died in 2004; they were married for 67 years. He had no immediate survivors. The gavel Rayburn gave to Mr. Swanson on Dec. 11, 1941, is today in the Capitol Visitor Center.