America's prosperity of the Roaring 20's vanished after the 1929 stock market crash. The era of the Great Depression was marked by massive unemployment at home and the solidification of facism in Europe. To address the nation's economic woes, Franklin D. Roosevelt offered the New Deal to a struggling constituency disinterested in Europe's problems.

But some American architects, builders and consumers were not disinterested in Europe's architectural ideas. Architectural and social manifestos of the 1920's must have seemed to be made for New Deal consciousness. Thus, despite Washington's well-established Beaux Arts momentum, new design ideas were being imported from Germany, France and Italy, as well as from Chicago and New York.

The "international" design movement idealized machines and machine images. Le Corbusier, a Swiss-born French architect who shared such notions with his contemporaries, was infatuated by 20th century technical artifacts, especially airplanes and ships. He talked about their functional forms derived inevitably from performance necessities, rather than from stylistic whim.

Like Germany's Walter Gropius, Erich Mendelsohn, and Mies Van der Rohe, he admired clean and purified lines, so well suited to motion and speed. He lauded efficient, appropriate use of materials and multi-system engineering.

Along with his Bauhaus counterparts, he rejected the literal application of historic motifs to buildings. Instead, he advocated the invention of new motifs expressive of the machine age. Buildings were mechanized tools to serve society. Design was a matter of social, economic and technological ethics.

How did Corbusier's ideas -- plus those of Louis Sullivan, Frank Lloyd Wright, the internationalists and other contemporary architects and artists -- affect the direction of Washington's architecture during the Roosevelt years?

One direction was taken by designers who embraced the Art Deco and Art Moderne styles, unquestionably "international" in spirit and appearance. Art Deco had begun in earnest with the 1925 Paris Exposition. Derived in part from turn-of-the-century Art Nouveau, it pushed jazz-era and age-of-speed themes.

Designs included angular, abstract geometrical motifs, forms with rounded edges and streamlined packaging. Industrial designers -- Raymond Loewy, Norman Bel Geddes, and others -- adopted streamlining as the appropriate image for the 1930's, and even Frank Lloyd Wright, borrowing from Japanese Shinto philosophy, had preached in 1930 the need to "be clean," to use "clean lines . . . for clean purposes."

Streamlining made practical sense for machines which had to move through air or water, but it became purely symbolic when applied to home appliances, furniture and buildings. Think of the toasters, chairs, lamps, ashtrays and diners of that era. Recall scenes from movies of the 1930's and early 1940's in which sets were dominated by sweeping horizontal lines, rounded corners, horizontal metal railings, glass block, neon tubes, flat roofs and doors with half-moon windows in them.

Throughout the Depression, streamlining must have suggested a utopian future, an escape from the present, a promise of things to come. What better place for Art Deco imagery than movie palaces? In every American city, architects designed theaters whose exteriors and interiors celebrated such escape with streamlines and "moderne" ornament.

Washington had its Penn Theatre on Capitol Hill, the Uptown on Connecticut Avenue and the Silver Theatre in Silver Spring (the latter designed by architect John Eberson for William Alexander Julian, former U.S. treasurer). The Silver was built in 1938 as part of the Silver Spring shopping center, one of the first such centers in the area and a prototypical example of Art Deco styling applied to commerical real estate.

Other familiar Art Deco/Art Moderne buildings in the nation's capital include the Shoreham Hotel by Joseph Abel (1930), the Hecht Co. warehouse on New York Avenue NE (1936) and numerous apartment buildings along Connecticut Avenue and 16th Street NW, particularly at, or above, Rock Creek Park.

In 1936, Clarence Stein and Hale Walker designed Greenbelt. They used brick and painted concrete block to impart lean and clean style to this cooperative New Deal community, amalgamating Art Deco and internationalist thinking.

Another stylistic direction, not totally unrelated to Art Deco, involved a kind of stripped classicism, sometimes referred to as between-the-wars rationalism. It characterized many of the monumental civic buldings constructed in facist Italy as well as in democratic America. Each building was composed like beaux arts edifices in plan and overall massing, including entrance columns and porticos, but they lacked the traditional layers of embellishing detail and ornament.

In 1930, Paul Cret designed the Folger Shakespeare Library on East Capitol Street, a building which author E. J. Applewhite describes as "an Art Moderne version of the stripped classical style." Cret attempted to reconcile traditional Beaux Arts composition with modernism's disdain for ornament, which is limited on the Folger's exterior or Art Deco aluminum grillwork and subtle stonework relief.

Former classicist Cret, while perhaps resisting and yet responding to the influences of Corbusier, the Bauhaus and Art Deco, went on to design the 1937 Federal Reserve Building at Constitution Avenue and 20th Street NW in the "starved" classical style. With Navy architect Frederick Southwick, he later designed the towering Bethesda Naval Hospital based on a conceptual sketch actually made by President Roosevelt.

As the 1940's began, two major projects in the modernist/classic mode appeared on the Virginia side of the Potomac: National Airport and the Pentagon. Of similar stylistic character are the D.C. Municipal Center on Indiana Avenue south of Judiciary Square, the Department of the Interior one block west of the Ellipse and the State Department building further west in Foggy Bottom.

All of these structures are undeniably rational with their diagrammatic, orderly plans and elevations. Their fundamental geometries are symmetrical and balanced. Some labeled them "government modern."

Of course, private-sector construction was curtailed substantially between 1930 and World War II's end in 1945. However, during this 15-year period of turmoil, the forceful proponents of modern design, although frequently unemployed, had been consolidating. Many European designers immigrated to the United States, where their modern rationale would at last gain enthusiastic, mainstream support from those who invest in and build real estate, as well as from those who design it.

Architects and clients who admired the efficiency, logic and potential cost-effectiveness of clean, streamlined, unadorned architecture would build more in Washington after the war then was built in the previous 15 decades.