During the years of 1898–1945, New York City consolidated. New York City became the capital of national communications, trade, and finance, and of popular culture and high culture. More than one-fourth of the 300 largest corporations in 1920 were headquartered there.David R. Goldfield and Blaine A. Brownell, Urban America: A History(2nd ed. 1990), p 299

The era began with the formation of the consolidated city of the five boroughs in 1898, with a total population of 3.4 million. New transportation links, especially the New York City Subway, opened in 1904, bound together the new metropolis. Increased immigration of Catholic and Jewish workers from Southern and Eastern Europe expanded the labor force until the World War ended immigration in 1914. Labor shortages during the war attracted African Americans from the Southeast, who headed north as part of the Great Migration. They sponsored the Harlem Renaissance of literature and culture celebrating the black experience.

The Roaring Twenties were years of glamour and wealth, highlighted by a construction boom, with skyscrapers built higher and higher in the famous skyline. New York's financial sector came to dominate the national and the world economies. The economy of New York City prospered after 1896, with a few short dips, until the decade-long Great Depression, which began with a Wall Street stock market crash in late 1929. The economy recovered by 1940 and flourished during the World War II years. The main bases of the economy were construction, ocean shipping, garments, machine tools, and printing. Labor unions rose and fell and rose again. New York boasted the nation's strongest financial system, a large upscale market for luxury goods, and a flourishing high culture based on many philanthropists, museums, galleries, universities, artists, writers, and publications.

The Democratic political machines in the boroughs generally controlled politics. However, they were finally overthrown in 1933 by reformers who elected and repeatedly re-elected Fiorello La Guardia. Heavy federal patronage helped convert the city into a stronghold of the New Deal coalition and the model of heavy government spending on infrastructure.For a visual overview of the era, see Eric Homberger, The historical atlas of New York City: A visual celebration of 400 years of New York City's history (Macmillan, 2005), pp 114–145.

Progressive Era: 1890s–1920s

The modern five boroughs, comprising the city of New York, were united in 1898. In that year, the cities of New York—which then consisted of present-day Manhattan and the Bronx—and Brooklyn were both consolidated with the counties of Queens and Staten Island.David C. Hammack, "Reflections on the Creation of the Greater City of New York and Its First Charter, 1898." New York Law School Law Review 42 (1988) pp: 693+ The total population was 3.4 million in 1900, leaping to 5.6 million in 1920 and leveling off at 7.9 million in 1950. The population was highly diverse in ethnicity, race, religion and class.Lawrence A. Cremin, American Education: The Metropolitan Experience 1876–1980 (1988) pp 576–577

The city went through an enormous growth in population, industry, and wealth. Major achievements included the building of the subway system by commercial companies. The city funded major new bridges between Manhattan and Brooklyn and Queens, which enabled commuting and the rise of an industrial base there. The city also expanded its port facilities, improved its traffic system, built hundreds of new elementary and high schools, and engaged in large-scale public health programs. Many early skyscrapers, including several of the world's tallest buildings, were erected in Manhattan.

Machine politics versus the reformers The politics of the consolidated city revolved around conflicts between the political machines and the reformers. In the quiet times, the machines had a solid core of supporters and usually exercised control of city and borough affairs; they also played a major role in the state legislature in Albany. Tammany Hall from the 1880s and onward built a strong network of local clubs that attracted ambitious middle-class ethnics.Roy V. Peel, The Political Clubs of New York City (1935).Martin Shefter, "The electoral foundations of the political machine: New York City, 1884–1897." in Joel Silbey et al. eds., The history of American electoral behavior (1978), pp. 263–298. In times of crisis however, especially in the severe depressions of the 1890s and the 1930s, the reformers took control of key offices, notably the mayor's office. The reformers were never unified; they operated through a complex network of independent civic reform groups, each focusing its lobbying efforts on its own particular reform agenda. Membership included civic-minded, well-educated middle-class men and women, usually with expert skills in a profession or business, who deeply distrusted the corruption of the machines.Richard Skolnik, "Civic Group Progressivism In New York City," New York History (1970) 51#5, pp. 411–439. Consolidation in 1898 multiplied the power of these reform groups, whenever they could agree on a common agenda such as consolidation itself.David C. Hammack, Power and Society: Greater New York at the Turn of the Century (1982), pp. 308–313.

There was no citywide machine. Instead, Democratic machines flourished in each of the boroughs, with Tammany Hall in Manhattan the most prominent. They typically had strong neighborhood organizations, known as "political clubs", as well as one prominent leader often called "the boss". Charles Murphy was the highly effective but quiet boss of Tammany Hall from 1902 to 1924. "Big Tim" Sullivan was the Tammany leader in the Bowery and the machine's spokesman in the state legislature along with Robert F. Wagner and Al Smith. Republican local organizations were much weaker, but they played key roles in forming reform coalitions. Most of the time they looked to Albany and Washington, D.C., for their sphere of influence.Jackson, Encyclopedia of New York City, (1996), pp. 914, 999, 1149–1151.Marvin G. Weinbaum, "New York County Republican Politics, 1897–1922: The Quarter-Century After Municipal Consolidation." New York Historical Society Quarterly (1966) 50#1, pp. 62–70.

The spirit of the Progressive Era infused New York politics, energizing the reformers with a condemnation of inefficiency, waste, and corruption. An emphasis was placed on expertise and scientific organization of large scale projects. Tammany Hall went along, under the new leadership of Charles Francis Murphy. It promoted a reform image itself, sponsored reformers as mayor, and downplayed overt forms of corruption, graft, and bribery.George J. Lankevich, American Metropolis: A History of New York City (1998), pp. 138–155. The Irish remained in control of Tammany, and the leadership had many opportunities for what Alderman George Washington Plunkett called "honest graft" such as an inside track to lucrative construction contracts without any stealing or committing illegal acts.

Three reformers became mayor. Seth Low, the president of Columbia University, united reformers and the Republicans in a fusion ticket that won the mayor's race in 1902. Low lacked the common touch and lost much of his working class support when he listened to Prohibitionists eager to crack down on the liquor business."Seth Low," in Jackson,Encyclopedia of New York City, (1996), p. 695.Steven C. Swett, "The Test of a Reformer: A Study of Seth Low, New York City Mayor, 1902–1903," New-York Historical Society Quarterly (1960) 44#1, pp. 5–41.

Tammany was back in 1904 with a prestigious reformer, George B. McClellan Jr., the son of the famous Civil War general and an experienced politician in his own right. William Jay Gaynor, reform judge, won the Tammany nomination in 1909. Fusion reformer John Purroy Mitchel, a favorite of President Woodrow Wilson, was elected in 1913. Mitchel had strong support from the progressives, enabling him to reorganize the bureaucracy, crackdown on vice, and make taxation more efficient. Mitchel's support for the Allies in the World War alienated Germans, and the working classes were alarmed at his plans for vocational education. He was defeated in 1917 by John Francis Hylan; Hylan was re-elected in 1921 and collaborated closely with Hearst until he was ousted by Al Smith and Tammany in 1925.Robert A. Slayton, Empire Statesman: The Rise and Redemption of Al Smith (2001), pp. 221–224.

Tammany realized it needed reformers on the ticket, but it had a hard time working with them. It needed McClellan to run for re-election in 1905 to beat off the tremendous challenge by independent publisher William Randolph Hearst. But in 1906 Tammany cut a deal and supported Hearst for governor, so McClellan broke with the machine.Ben Procter, William Randolph Hearst: The Early Years, 1863–1910 (1998), pp. 203–211, 220–227. Gaynor proved much more independent than expected and was denied renomination.Lately Thomas, The Mayor who Mastered New York: The Life and Opinions of William J. Gaynor (1969).

Transportation

The municipal consolidation precipitated greater physical connections between the boroughs. The building of the New York City Subway opened with the first IRT line in 1904. Initially the Interborough Rapid Transit Company (IRT) and Brooklyn-Manhattan Transit Corporation (BMT) systems (with a third system, the Independent Subway System or IND, to be incorporated in 1925) were separate. They immediately became a force for further population spread and development.

The opening of the Williamsburg Bridge in 1903 and the Manhattan Bridge in 1909 further connected Manhattan to the rapidly expanding bedroom community in Brooklyn. The world-famous Grand Central Terminal opened as the world's largest train station on February 1, 1913, replacing an earlier terminal on the site. The Pennsylvania Station, a similarly large and grand railway station several blocks to the west that was torn down in 1963, had opened in 1910.William D. Middleton, Grand Central, the World's Greatest Railway Terminal (1977).

Immigrant life

European immigration increased rapidly during the early 20th century and suddenly stopped in 1914 due to World War I and the Emergency Quota Act allowing new residents to assimilate in American life. The new arrivals were Italian and Polish Catholics, as well as Yiddish-speaking Jews from Eastern Europe.Irving Howe, World of Our Fathers: The Journey of the Eastern European Jews to America and the Life They Found and Made (1976). There were smaller but steady streams of "Old immigration" sources in Ireland, Britain and Germany. The residents of Little Germany, in what is now the East Village, dispersed to more affluent neighborhoods and were replaced by growing numbers of poor immigrants on the Lower East Side.Dorothee Schneider, Trade Unions and Community: The German Working Class in New York City, 1870–1900 (1994)

Jews

In 1850 about a third of the 50,000 American Jews lived in New York; they spoke German (not Yiddish), were active in Reform congregations, and took major leadership roles in the city's banking, financial, merchandising, and clothing industries. An entirely different group of 1.4 million poor Yiddish-speaking Jews from Russia and Eastern Europe fled pogroms and anti-Semitism between 1880 and 1914. Over one million lived in New York, where by 1910 they comprised a fourth of the city's population. Many became entrepreneurs setting up small shops; the majority operated sewing machines and worked in the city's many small clothing factories.Jackson, Encyclopedia of New York City, (1996) pp 620–621