Summary of "Only Yesterday: An Informal History of the 1920s"

Core Idea

Only Yesterday treats the 1920s as a still-fresh “contemporary history” of American public mind and daily life, from Armistice Day 1918 to the stock-market crash of late 1929.
Allen’s central claim is that the decade was defined less by formal policy than by changing moods: postwar disillusion, moral revolt, business triumph, mass spectacle, and finally collapse.
The book’s stakes are national: the 1920s remade manners, sex, religion, business, media, crime, and politics, then ended in the crash and Depression that exposed how fragile the era’s confidence had been.

The Postwar Break: Disillusion, Red Scare, and “Normalcy”

The war ended with Wilsonian idealism, but the “bubble” was quickly punctured by disillusion, labor conflict, inflation, and a turn toward anti-radicalism.
Allen stresses that the Red Scare was real but wildly exaggerated: the actual radical movements were small, yet bombs, strikes, and fear of Bolshevism produced a climate of hysteria.
The Palmer raids, deportation fever, and attacks on socialist meetings show how wartime habits of summary action carried into peace.
Prohibition was pushed through by wartime moral militancy and anti-German feeling, but enforcement was doomed from the start by geography, loopholes, and tiny federal manpower.
Wilson’s tragedy, in Allen’s account, lies in his inability to compromise: he went to Paris to build the League of Nations, but returned home insisting on the Treaty as a moral whole, just as the country was turning against crusading idealism.
Henry Cabot Lodge personifies the anti-Wilson reaction: nationalist, Senate-centered, and determined to keep the U.S. free of entangling alliances.
Harding’s rise marks the national turn to “normalcy”: he was chosen because he was genial, unthreatening, and restorative rather than visionary.
Allen’s portrait of Harding is bluntly double-edged: personally reassuring, but politically weak, ill-informed, and surrounded by the Ohio gang and administrative corruption.

The New Mass Culture: Manners, Sex, Media, and Spectacle

Allen’s most famous theme is the “Problem of the Younger Generation”: a revolt among respectable sons and daughters over sex, smoking, drinking, dancing, dress, and parental authority.
The flapper becomes the visual emblem of change: shorter skirts, bobbed hair, cosmetics, looser dresses, and a new body ideal aimed at youth and allure rather than domestic respectability.
The new dance culture, especially the fox-trot and saxophone-driven music, makes courtship physically closer and more openly sensual.
Allen links this moral shift to multiple forces: war disillusionment, women’s emancipation, Freud, prohibition, automobiles, confessional magazines, and movies.
Women’s suffrage mattered symbolically, but the larger change was practical emancipation from housework through appliances, ready-made goods, laundries, canned foods, and paid employment.
The automobile and prohibition together reshaped social life: cars created private spaces beyond supervision, while speakeasies and cocktail parties replaced the old masculine saloon with mixed drinking.
New vocabularies of sex psychology and modern science spread through popularization, making terms like libido, inferiority complex, and Oedipus complex part of ordinary speech.
Allen treats this as a real cultural revolution, but also as a confusing one: old restraints fell faster than a stable new code could form.

Business, Prosperity, and the Age of Ballyhoo

After the 1921 slump, prosperity returned and became the era’s dominant fact; Allen calls the businessman the period’s dictator of destinies.
The boom rested on mass production, Europe’s weakness, careful management, and Republican confidence, but also on installment buying and stock-market speculation, which pulled future income into the present.
The automobile, radio, appliances, chain stores, movies, and advertising created a new consumer civilization; business and culture increasingly used the same language of salesmanship and appeal.
Advertising shifts from describing products to selling emotions, status, youth, and fear; Allen treats campaigns like Listerine’s halitosis pitch as archetypal.
The market of the 1920s becomes a public obsession before 1929, but the crash reveals how far speculation had outrun reality.
In Allen’s phrase, the decade is an age of “ballyhoo”: people are mobilized by spectacles, from crosswords and murder trials to Scopes, Lindbergh, and prizefights.
The press and radio do not invent every craze, but they amplify whatever can be turned into a national one-tune-at-a-time event.

Highbrows, Fundamentalists, Crime, and the Crash

Allen sees a Revolt of the Highbrows against mass standardization, business culture, censorship, and majority morality, voiced by Mencken, Sinclair Lewis, and a new urban intellectual class.
That revolt is sharpened by scientific skepticism and by the split between Fundamentalists and Modernists in Protestantism; the Scopes trial dramatizes the clash between literalism and modern thought.
Yet the revolt is ambivalent: it debunks old certainties but often leaves behind emptiness, irony, and the question of what replaces lost faith.
Prohibition proves to be the great failure of moral legislation, producing bootlegging, speakeasies, mixed drinking, and eventually a national underworld.
Al Capone and Chicago gangsterism embody the consequences: organized vice, political corruption, theatrical violence, and a racketeering economy built on intimidation and bribery.
Allen extends the same pattern to land booms, especially Florida: boosterism, speculation, and fantasy wealth create a bubble that collapses under default and hurricane.
The culminating disaster is the stock-market crash of 1929, which Allen presents as both an economic break and a psychological reversal after years of inflated confidence.
The crash destroys paper wealth, exposes structural weakness, and ends the era’s mood of effortless prosperity.
The opening of the 1930s brings partial stabilization in some cultural habits, but also the Depression, which makes clear that the 1920s were not just a carefree decade but a fragile order now broken.

What To Take Away

The 1920s in Allen’s telling are best understood as a struggle between postwar disillusion and new mass confidence, with neither side fully stable.
The decade’s signature changes were cultural as much as economic: sex, dress, leisure, media, religion, and status were all reorganized around modernity.
Many “victories” of the age were unstable or self-undermining: prohibition bred illegality, prosperity bred speculation, publicity bred ballyhoo, and reform bred backlash.
Allen’s final judgment is not nostalgic or celebratory; the 1920s matter because they created the modern America that entered the Depression.