Washington, D.C., has evolved over the last two centuries from a collection of wetlands, farms, and sparsely developed tracts of land into a world-class city with a diverse population, vibrant neighborhoods, numerous religious centers, and terrific restaurants, museums, theaters, and music venues—a fitting host for our nation’s government. There is one complaint lodged against Washington, D.C., however, that has not changed since it was designated as the U.S. capital more than 200 years ago: the summer heat. How to handle Washington’s often stifling heat and humidity has been a perennial challenge for the U.S. Senate.
Lawmakers of the 19th century were usually away from the capital during the hottest months of the year. Until adoption of the Twentieth Amendment in 1933, Congress convened in December, typically stayed in session for six or seven months, and then adjourned sine die in June or early July. Short second sessions convened in December and adjourned in March.1
Complaints from lawmakers in the 1840s about the ineffective heating and cooling of the Capitol led supervising engineer Captain Montgomery Meigs to focus on improved ventilation during construction of the new wings of the Capitol in the 1850s. The Senate wing, featuring a new windowless Chamber, opened in 1859, equipped with large steam-engine powered fans to draw in outside air and push it up through registers in the floor. This system proved to be insufficient. In their first summer session there, during June 1860, senators complained of the hot, stale air in the Chamber. If not for the pressing business of the Civil War, the Senate might have adopted proposals to knock down walls and extend the Chamber to the building’s outside perimeter to allow access to open windows. An 1865 report identified the glass ceiling of the Chamber as a major source of excessive heat. The stained glass allowed the sun’s rays to penetrate and heat the room, and in the evening the gas lights that illuminated the room pushed the temperature even higher. Making matters worse, the air sucked into the building tended to be dirty and dusty, as it was drawn from ground-level inlets on the Capitol terrace.2
In 1872 the Senate once again considered plans to rebuild the Chamber. Senator Roscoe Conkling of New York was adamant about the need for a change. “Who ever heard of putting men or animals in a box inside a building,” he asked, “shut out on every hand from the outer air.” Nevertheless, the Senate only approved minor changes to the ventilation system. In 1889 a stone tower was built on the Capitol grounds to increase the volume of air brought into the Senate wing, relatively free of the dirt and dust brought in by ground-level intakes.3
These changes helped to purify the air but did little to keep the Chamber cool, which was especially problematic during years when sessions continued into August. In the late 19th century, for example, the mid-summer heat wreaked havoc on the Senate’s sartorial decorum. Newspaper reporters complained about the many lawmakers who went without a vest or jacket in the halls and cloakrooms. “Dignity has gone to the wind,” wrote one correspondent. A jacket was required on the Chamber floor, and some turned to linen suits to stay cool. Reporters observed that members of both the House and the Senate took great advantage of the marble bathtubs in the Capitol basement to refresh themselves.4
In 1890 the Capitol gained electricity, and with it came a new tool for fighting the summer heat. Electric fans were placed strategically in Capitol hallways, often blowing over blocks of ice to cool the air. Some suggested using giant blocks of ice to cool the Chamber itself, but an 1895 report on Chamber ventilation by engineer S. H. Woodbridge, commissioned by the Senate Rules Committee, pointed out that cooling 600,000 cubic feet of air from 95 to 80 degrees would require melting 1,150 pounds of ice. Woodbridge also reported that “the air so cooled would be more uncomfortable and dangerous than the hotter air of 95 degrees because of its excessive humidity.” To remedy that problem would require cooling a ton of ice per hour.5
The Senate again turned to new technology for a solution. In 1895 senators approved a major renovation of the Chamber’s ventilation system, installing new fans beneath the Chamber and a refrigerant machine that promised to deliver cooled air to both senators on the floor and visitors seated in the galleries. This system also proved to be inefficient, however, cooling the air by no more than five degrees. In 1910 the Bureau of Standards of the Department of Commerce and Labor developed a method for removing humidity from the air using a calcium chloride solution pumped through radiator pipes. In 1912 Congress appropriated funds to put this refrigerator system in place, but the plan was scrapped after the superintendent of the Capitol reported that installation required dramatic changes to the existing ventilation system with a cost dramatically higher than Congress anticipated.6
By the early 20th century, the Senate Chamber had gained the reputation of a death trap. Between 1916 and 1924, 22 incumbent senators died. When Senator Royal Copeland of New York, a practicing physician and former commissioner of the New York City Board of Health, took office in 1923, he blamed the poor quality of the Chamber’s air for the deaths. Copeland introduced a resolution directing Capitol officials to consult with leading architects to develop a plan to improve conditions in the Chamber. The Senate approved Copeland’s resolution in June 1924 as the increasingly warm late-spring days again called attention to this perennial problem. Another 12 senators died in office over the next four years.7
The firm of Carrere & Hastings, designers of the Senate Office Building that opened in 1909, revived the idea of removing several walls to extend the Chamber to the Capitol's northern exterior wall. In removing these interior walls, the Senate would have to sacrifice the Marble Room (a popular senators-only gathering spot), the President's Room, and the vice president's formal office, but it would provide windows to the outside world that senators had pined for since the Chamber opened in 1859.
In April 1928 Copeland, a member of the Senate Appropriations Committee, succeeded in adding $500,000 to an appropriations bill for reconstructing the Senate Chamber. Copeland’s plan was not the only one under consideration. The House, in its version of the bill, proposed funding to allow the Architect of the Capitol to accept bids for “an improved and modern system . . . for conditioning the air” of the Hall of the House and the Senate Chamber. The final bill included both appropriations, but only one plan came to fruition. In 1928 the Carrier Corporation won the contract to install in the Chambers of the House and Senate a new technological innovation, which it called "manufactured weather." The system was installed in the Hall of the House in December 1928 and work began on the Senate Chamber early the following year. By August 1929, in the midst of an unusually long session, the Senate had its first air-conditioning system. With the new system in place, the Architect of the Capitol dropped the plan to redesign the Chamber.8
Between 1935 and 1939, air-conditioning was expanded to the rest of the Capitol and to the Senate Office Building. “Summer work,” a reporter commented, “is no longer the broiling death-dealing business for elder Congressmen that it used to be.” Air-conditioning in the Capitol and the office buildings meant, according to another reporter, that lawmakers were “privileged to wave their arms or pound their typewriters or evolve masterpieces of statecraft in relative comfort.”9
Yet even this air-conditioning system proved inadequate for the hottest days, due in part to the Chamber’s glass ceiling (which was finally removed in a 1949 renovation). Plus, no matter how well cooled the Capitol was, senators still had to contend with the city’s summertime climate outside the building. Few members of Congress lived in air-conditioned homes at this time, which made the air-cooled Senate Chamber a double-edged sword. As one writer opined, walking outside or into a non-air-conditioned building became “twice as oppressive.” Some members fled the city, such as a group of five senators who rented a bachelor pad in Bethesda, Maryland, during the summer of 1929 to escape the heat of the city while their wives were out of town.10
Still, the air-conditioning led to a much more comfortable environment in the Capitol, and it had arrived just in time. Adoption of the Twentieth Amendment to the Constitution in 1933, which moved the start date of each congressional session to January, meant that long Senate sessions lasting well into summer were about to become much more common.
1. For session dates, see https://www.senate.gov/legislative/DatesofSessionsofCongress.htm.
3. Congressional Globe, 42nd Cong., 2nd sess., June 7, 1872, 4353, quoted in Allen, History of the U.S. Capitol, 364; Joint Select Committee on the Senate Chamber and the Hall of the House of Representatives, Improvement of the Halls of Congress, S. Rep. 38-128, 38th Cong. 2nd sess., February 20, 1865, 6; Glenn Brown, Glenn Brown's History of the United States Capitol (Washington, D.C.: U.S. Capitol Preservation Commission, 1994; originally published 1900), 419.
5. Senate Committee on Rules, Report on the Heating and Ventilation of the Senate Wing of the United States Capitol, Washington, D.C., S. Rep. 54-713, 54th Cong., 1st sess., December 14, 1895, 15; Brown, Glenn Brown's History of the United States Capitol, 423; “Thermometer Reached 100 Degrees in the Shade,” Baltimore Sun, June 24, 1894, 2.
6. “Senate Chamber Transformed,” Hartford Courant, November 30, 1896, 6; “Try New Device to Cool Capitol,” Chicago Daily Tribune, July 22, 1910, 14; “Refrigerated Air for Congressmen,” Boston Daily Globe, August 18, 1912, SM-5; Ventilation of the Senate Chamber, S. Doc. 62-1061, 62nd Cong, 3rd sess., February 3, 1913; Refrigerating Apparatus, United States Capitol, H. Doc. 62-1419, 62nd Cong., 3rd sess., February 24, 1913.
8. Senate Committee on Appropriations, Legislative Appropriation Bill, 1929, S. Rep. 70-857, 70th Cong., 1st sess., April 21, 1928; An Act Making appropriations for the Legislative Branch of the Government for the fiscal year ending June 30, 1929, Public Law 70-386, 70th Cong, 1st sess., May 14, 1928, 45 Stat. 526; Joseph M. Siry, Air-Conditioning in Modern American Architecture, 1890–1970 (University Park, PA: Pennsylvania State University Press, 2021), 84–91; Allen, History of the U.S. Capitol, 401–3.