By the 1920s, each state in the United States had passed public laws that stipulated a certain day to be Arbor Day or Arbor and Bird Day observance.

By the late 1920s Potter and her Hill Top farm manager Tom Storey had made a name for their prize-winning Herdwick flock.

By the 1920s, composers of Tin Pan Alley and Broadway used ballad to signify a slow, sentimental tune or love song, often written in a fairly standardized form ( see below ).

By the late 1920s, New York writers other than Fitz Gerald were starting to use " Big Apple " and were using it outside of a horse-racing context.

By the 1920s, the emerging middle and working classes were powerful enough to elect a reformist president, Arturo Alessandri Palma.

By the 1920s, many newspapers had a comics page on which many strips were collected together.

Additional milieu were provided by Chaosium with the release of Dreamlands, a boxed supplement containing additional rules needed for playing within the Lovecraft Dreamlands, a large map and a scenario booklet, and Cthulhu By Gaslight, another boxed set which moved the action from the 1920s to the 1890s.

By the early 1920s, unit operations became an important aspect of chemical engineering at MIT and other US universities, as well as at Imperial College London.

By the late 1920s, Al Capone and the Mob were inspiring not only fear, but piquing mainstream curiosity about the American underworld.

By the 1920s, the U. S. reached what is still its era of greatest-ever output, producing an average of 800 feature films annually, or 82 % of the global total ( Eyman, 1997 ).

By the 1920s Lewis Fry Richardson's interest in weather prediction led him to propose human computers and numerical analysis to model the weather ; to this day, the most powerful computers on Earth are needed to adequately model its weather using the Navier – Stokes equations.

By the 1920s, the idea of an Israelite conquest of Canaan-the story of the book of Joshua-was not supported by the archaeological record.

By the 1920s, Hearst, was the owner of a chain of newspapers from coast to coast.

By the 1920s, the diatonic harmonica had largely reached its modern form.

By the 1920s however the Senate had lost much of its original influence, and hence no sitting senator had been known to have serious aspirations of becoming prime minister whilst remaining in the Senate.

By the 1920s the number of cars had soared to 60, 000.

By the early 1920s, however, the inherent limitations of this type of engine had rendered it obsolete, with the power output increasingly going into overcoming the air-resistance of the spinning engine itself.

By the 1920s psychoanalysts assumed that homosexuality was pathological and that attempts to treat it were appropriate, although psychoanalytic opinion about changing homosexuality was largely pessimistic.

By the late 1920s the resistance movement against colonial rule had gathered widespread support during the mistreatment of the Samoan people by the New Zealand administration.

By the late 1920s, however, those employing only optical and electronic technologies were being explored.

By the late 1920s, economic performance had stabilised, but the overall situation was disappointing, for Britain had clearly fallen behind the United States and other countries as an industrial power.

By the 1920s, however, this boisterous folksiness had diminished.

By the end of the 1920s Corbusier was already an internationally known architect.

By the 1920s, the British Government were seeking a replacement for their book code systems, which had been shown to be insecure, and which proved to be slow and awkward to use in practice.

" By the 1920s, Birmingham was the 19th largest city in the U. S and held more than 30 % of the population of the state.

By the 1930s, a series of favorable biographies enhanced his prestige.

By the 1930s, statisticians and models built on statistical reasoning had helped to resolve these differences and to produce the neo-Darwinian modern evolutionary synthesis.

By the 1930s boats built of all steel from frames to plating were seen replacing wooden boats in many industrial uses, even the fishing fleets.

By 1921 he was the majority owner, maintaining that status into the 1930s.

By the late 1930s, Thomas was embraced as the " poetic herald " for a group of English poets, the New Apocalyptics.

By the 1930s, Ben Duncan and others popularized streamlined trap kits leading to a basic four piece drum set standard: bass, snare, tom-tom, and floor tom.

By the 1930s, the five-line cinquain verse form became widely known in the poetry of the Scottish poet William Soutar.

Despite the revivalists ' various political views and different opinions regarding the nature of authentic folk music, they all shared an understanding of Americanism that grounded the nation's identity in cultural pluralism and political democracy " By the end of the 1930s they along with the musicians and others had turned American folk music into a social movement.

By the 1930s, Italian fascism had created a review board for popular culture.

By the 1930s it was in wide use.

By the late 1930s and the 1940s, Italian Fascism completely denounced capitalism as an obsolete and oppressive system, Mussolini in 1940 at the entry of Italy into World War II, said:

By the 1930s, several faith healers drew large crowds and established worldwide followings.

By the early 1930s Gardner's activities had moved from those exclusively of a civil servant, and he began to think of himself more as a folklorist, archaeologist and anthropologist.

By the 1930s the place would evolve to become her greatest legacy, the Whitney Museum of American Art, on the site of today's New York Studio School of Drawing, Painting and Sculpture.

By the 1930s, Genosha Bay later became a United States extraterritorial prison which hold prisoners of the worse cases from around the world and was notorious for practicing inhumane punishments on its prisoners ranging from sleep deprivations and water torture.

By the end of the 1930s, the PNH was the only organized functioning political party in the nation.

By the late 1930s it had become dangerous to be publicly associated with religion.

By the 1930s, the guitar began to displace the banjo as the primary chordal rhythm instrument in jazz music, because the guitar could be used to voice chords of greater harmonic complexity, and it had a somewhat more muted tone that blended well with the upright bass, which, by this time, had almost completely replaced the tuba as the dominant bass instrument in jazz music.

As for the contradiction between German rearmament and his message of peace, Ribbentrop argued to whoever would listen that the German people had been “ humiliated ” by the Versailles treaty, that Germany wanted peace above all, and German violations of Versailles were part of an effort to restore Germany's " self-respect " By the 1930s, much of British opinion had been convinced that the treaty was monstrously unfair and unjust to Germany, so as a result, many in Britain like Thomas Jones were very open to Ribbentrop ’ s message that if only Versailles could be done away with, then European peace would be secured.

By the later 1930s government began to intrude on ordinary Africans through marketing controls, stricter educational supervision, and land changes.

By the 1930s, approximately 30, 000 white settlers lived in the area and gained a political voice because of their contribution to the market economy.

By 1870 Liberia had sunk into financial crisis, which dragged on into the 1930s.

By the late 1930s the Luftwaffe had no clear purpose.

By the 1930s it was clear that if the Soviet cinema was to compete with its Western counterparts, it would have to give audiences what they wanted: the glamour and fantasy they got from Hollywood.

By the 1930s, many revisions of the rules developed that were substantially different from Babcock's classical version ( including some that were considered fundamentals in other variants, such as the notion of a standard hand ).