On November 15, 1889, a coup d’état overthrew the monarchy and installed Field Marshal Deodoro da Fonseca as president, proclaiming the Republic of the United States of Brazil. Discontent with the Empire had been growing among various sectors, mainly the Church and the Military. Both acted to depose the old monarch Dom Pedro II and install a new regime aided by Brazilian republicans. The provisional government  started hesitantly and was maintained by force since support to the republican cause was not widespread and the Monarchy was still popular among Brazilians. A new constitution in 1891 established the country's armed forces as permanent national institution responsible for the maintenance of law and order, which frequently came under threat throughout the period. Even among the Armed Forces, there were upheavals, the Navy faced the first Revolt of the Armada in that same year, followed by a second in 1893 and the Revolt of the Lash (Revolta da Chibata in Portuguese) in 1910. Social unrest fueled by claims for landownership combined with religious elements generated violent conflicts such as the Canudos Campaign from 1893-1897 and the Contestado Rebellion of 1912-1916.  As domestic industries increased in Brazil during period of 1893 to 1930, so too did organized labor, with the resultant rise of strikes, protests, and urban conflicts throughout the country. Coffee's dominance of Brazil's exports concentrated political power in the states of Brazil's Southeast Region during the First Republic, which is popularly called the República Oligárquica (the Oligarch's Republic) for its "política do café com leite" (politics of coffee with milk), under which the presidency alternated between politicians from the state of São Paulo, one of the country's chief producers of coffee, and the state of Minas Gerais, known for its dairy production. The arrangement was defied by the Coluna Prestes from 1925 to 1927, a military and political movement against the oligarchical republic.

In the United States, the period from 1889 to 1930 is likewise one of drastic economic and political change. Beginning with the Gilded Age, moving on through the Progressive Era, the Roaring Twenties and the onset of the Great Depression, this period saw cycles of expansion and contraction in the stock market, the rise of activism in labor and the civil rights of Black Americans and women, and the passage of the 16th, 17th, 18th, and 19th amendments to the Constitution. ;With its coast-to-coast settlement complete by 1889, the United States also began to take its first steps at asserting power on the international stage. Through events such as the First International Conference of American States (1889) and policies such as the Roosevelt Corollary to the Monroe Doctrine (1904), the United States hoped to carve out a sphere of American influence in the Americas and displace that of the European powers. The third Pan-American Conference held in Rio de Janeiro in 1906, marked a milestone in the hemispheric relations with the first visit of an American Secretary of State, Elihu Root, to South America. Despite periods of isolationism, further programs like President William Howard Taft's Dollar Diplomacy and Woodrow Wilson's internationalism marked a definitive trend toward the rise to prominence of American political and business leaders n the international affairs of the 20th century.

Thanks in part to the efforts of Brazil's most notable Minister of Foreign Affairs, the Barão do Rio Branco, as well as to Ambassador Joaquim Nabuco, Brazil's First Republic marks the beginning of "the special relationship" between Brazil and the United States that would last until the 1970's. In trade, the United States became the primary destination for Brazil's export goods, while the United States displaced Britain as Brazil's main source of manufacturing imports. By assembling squadrons of ships crewed by American mercenaries to put down Brazil's naval revolt of 1893, American businessman Charles Ranlett Flint and the American navy initiated a long tradition of American intervention in Brazil's domestic political affairs. On the global stage, the United States supported the settling of many international boundary disputes in ways that favored Brazil's expansion while Brazil lent support to American leadership in international cooperation. Though Brazil's First Republic would end with the Revolution of 1930, commercial, military, and political cooperation between the two countries would grow for decades to come.

Key events

• Brazil--History--Naval Revolt, 1893-1894
• Brazil--History--Naval Revolt, 1910
• Brazil--History--Revolution, 1924-1925
• Coluna Prestes (Revolutionary movement)
• International American Conference (1st : 1889-1890 : Washington, D.C.)
• International American Conference (3rd : 1906 : Rio de Janeiro, Brazil)

Key figures

• Fonseca, Deodoro da, 1827-1892
• Nabuco, Joaquim, 1849-1910
• Prestes, Luís Carlos, 1898-1990
• Rio Branco, José Maria da Silva Paranhos Júnior, Barão do, 1845-1912
• Root, Elihu, 1845-1937

Key groups

• Pan American Union

Key subjects

• Brazil--Foreign relations--1889-1930
• Brazil--Politics and government--1889-1930