influence to limit working hours as early as 1867. At the same time, New York's agricultural output peaked. Focus changed from crop-based to dairy-based agriculture. The cheese industry became established in the Mohawk Valley. By 1881, the state had more than 241,000 farms. In the same period, the area around New York harbor became the world's oyster capital, retaining that title into the early twentieth century. Immigration increased throughout the latter half of the 19th century. Starting with refugees from the Great Famine of Ireland in the 1840s, New York became a prominent entry point for those seeking a new life in the United States. Between 1855 and 1890, an estimated 8 million immigrants passed through Castle Clinton at Battery Park in Manhattan. Early in this period, most immigrants came from Ireland and Germany. Ellis Island opened in 1892, and between 1880 and 1920, most immigrants were German and Eastern European Jews, Poles, and other Eastern and Southern Europeans, including many Italians. By 1925, New York City's population outnumbered that of London, making it the most populous city in the world. Arguably New York's most identifiable symbol, Liberty Enlightening the World (the Statue of Liberty), a gift from France for the American centennial, was completed in 1886. By the early 20th century, the statue was regarded as the "Mother of Exiles"—a symbol of hope to immigrants. New York's political pattern changed little after the mid–19th century. New York City and its metropolitan area was already heavily Democrat; Upstate was aligned with the Republican Party and was a center of abolitionist activists. In the 1850s, Democratic Tammany Hall became one of the most powerful and durable political machines in United States history. Boss William Tweed brought the organization to the forefront of city and then state politics in the 1860s. Based on its command of a large population, Tammany maintained influence until at least the 1930s. Outside the city, Republicans were able to influence the redistricting process enough to constrain New York City and capture control of the Legislature in 1894. Both parties have seen national political success: in the 39 presidential elections between 1856 and 2010, Republicans won 19 times and Democrats 20 times. 1901 through the Great Depression By 1901, New York was the richest and most populous state. Two years prior, the five boroughs of New York City became one city. Within decades, the city's emblem had become