With the spread of direct elections and the initiative and referendum, and the adoption of the two amendments to the Federal Constitution authorizing an income tax[73] and the popular election of Senators, the milder demands of Populism were secured. At the same time, the prosperity of the farmers and the enormous rise in ground values which accompanied the economic advance of the country removed some of the most potent causes of the discontent on which Populism thrived. Organized Populism died a natural death. Those Populists who advocated only political reforms went over to the Republican and Democratic parties; the advocates of radical economic changes, on the other hand, entered the Socialist ranks. Socialism, as an organized movement in the United States, runs back to the foundation of the Social-Democratic Workingmen's party in New York City, in 1874, which was changed into the Socialist Labor party three years later,--a party that still survives. This group did not enter into national politics until 1892, although its branches occasionally made nominations for local offices or fused with other labor groups, as in the New York mayoralty campaign of 1886. In its vigorous propaganda against capitalism, this party soon came into collision with the American Federation of Labor, established in 1886, and definitely broke with it four years later when the latter withheld a charter from the New York Central Federation for the alleged reason that the Socialist Labor party of that city was an affiliated organization. After the break with the American Federation, this Socialist group turned for a time to the more radical Knights of Labor, but this new flirtation with labor was no more successful than the first, and in time the Socialist Labor party declared war on all the methods of American trades-unionism. Its gains numerically were not very significant; it polled something over twenty thousand votes in 1892 and over eighty thousand in 1896--the high-water mark in its political career. Its history has been a stormy one, marked by dissensions, personal controversies, and splits, but the party is still maintained by a decreasing band of loyal adherents.