Romani in the United States are Americans descended from the ethnic Roma or Romani people. Roma in the United States refers to Roma, which is a specific group falling under the umbrella term Romani. Roma and Romani are not synonyms. Roma is a plural noun which means "men" or "husbands" and is used as an ethnic endonym by some Romani communities. Romani is an adjective which, in English, may also be used as a noun. It is estimated that there may be as many as one million Americans of Romani ancestry in the United States today. Though the Romani population in the United States has largely assimilated into American society, there is a noticeable concentration of Roma in Oregon, and American Roma communities can be found in most major metropolitan areas. 
Commonly referred to as "Gypsies", the Roma, ethnically and genealogically disparate from other Europeans, began settling in America in the mid 19th century, fleeing centuries of persecution in Europe. Americans were and are largely unaware of the cultural and historical prejudices about Roma held by Europeans, and though American Roma are cautious about the stigma associated with their heritage, they do not face discrimination or bigotry as they do in Europe. As a result, the social and economic position of Roma in the United States is substantively more favorable than in Europe, with many running successful family-owned businesses, and blending seamlessly into the community.
The largest wave of Roma immigrants came after the abolition of Roma slavery in the Balkans in 1864. Roma immigration to the United States has continued at a steady rate ever since, though a large-scale surge of Roma immigration followed the 1989 collapse of Communism in eastern Europe.
Due both to the size of the American Roma population and the absence of a historical and cultural presence, such as the Romani have in Europe, Americans are largely unaware of the existence of the Roma as a people, associating the term "gypsies" with a trade or profession more than a cultural and ethnic heritage. Due to the term's lack of significance within the United States, many Roma do not use the term around non-Roma: identifying themselves by nationality rather than heritage. The U.S. Census does not distinguish Roma as a group, since it is neither a nationality nor a religion. However, Romani Americans gained increased visibility in April 2012 with the premiere of TLC's program My Big Fat American Gypsy Wedding, an American version of the UK television series My Big Fat Gypsy Wedding.
The Romanichal, the first Roma group to arrive in North America in large numbers, came to America from the British Isles around 1850. Eastern European Roma, the ancestors of most of the Roma population in the United States today, began immigrating to the United States on a large scale over the latter half of the century, following their liberation from slavery in Romania and the Balkans. This wave of Roma immigration comprised Romani-speaking peoples like the Kalderash, Machvaya, Lovari and Churari, as well as ethnically Romani groups that had integrated more with Eastern European society, such as the Boyash (Ludari) of Romania and the Bashalde of Slovakia. Roma immigration, like all Eastern European migration, was severely limited during the Soviet era in Eastern Europe, but picked up again in the 1990s after the fall of the Eastern Bloc.
Roma: A heterogeneous group including subcultures such as Kalderash, Lovari, Machvaya, Gurbeti, and others who began coming to the United States following the gradual abolition of Romani slavery between 1848 to 1864 in the principalities of Wallachia and Moldavia, now Romania and Moldova, which at the time were vassal states of the Ottoman Empire. Roma began immigrating in the late 1800s, initially settling in cities throughout the Northern United States as well as some cities South of the Mason-Dixon line such as Baltimore and represent the largest Romani ethnic group living in America.  New waves of Roma are coming since the early 1990s due to the decline of living conditions for Roma in Eastern Europe following the fall of the communist regimes which provided Roma with housing, employment, and healthcare, although Romani culture was still repressed in some regards. The unleashing of unfettered market liberalism also led to ethnic scapegoating and pogroms against Roma, as racist and fascist political movements grew.
Ludar: Hailing from North of the Balkans, Hungary, and the Banat, the Ludari, also known as Rudari, Boyash, or Banyash, are another subculture of Roma who arrived during the late 19th and early 20th centuries. 
Romanichals: The first Romani group to come to the British colonies, the Romanichals were deported from Britain as slaves as early as the 1600s. Romanichals are not considered Roma, but they are Romani. Romanichals also use the spelling "Romany" more frequently. Some more may have arrived from the British Isles around 1850, and settled into agrarian lifestyles throughout the United States.
Hungarian-Slovak Romani: Similar to the Roma, the Roma of Northern Hungary largely settled in industrial cities of the Northern United States near the turn of the century. Among Roma from these areas were Olah, Romungre, and Bashalde immigrants. They were noted for their musical traditions and popularized "Gypsy music" in the United States by performing in cafes, night clubs and restaurants. Their prevalence in show business made Hungarian-Slovak Roma the most visible of the Roma groups arriving in America at the turn of the century and helped to shape the modern American idea of a "gypsy".
Black Dutch: Another American Romani group whose roots go back to the 17th century Dutch colonies in what is now New Jersey and parts of the states of New York, Connecticut, Maryland, Delaware, and Pennsylvania. According to Shoemaker (1924), many of them later integrated with the Pennsylvania Dutch (German) community. They were called "Yansers" in New York. As with the Romany, the ethnonym "Roma" is considered inappropriate by most members of the community because they originate from the Sinti community (Romani people from German-speaking areas). Melungeons may be a related group. The term Black Dutch has also been used by people of American Indian descent who wanted to hide their origins.
1 Poles came to the United States legally as Austrians, Germans, Prussians or Russians throughout the 19th century, because from 1772-1795 till 1918, all Polish lands had been partitioned between imperial Austria, Prussia (a protoplast of Germany) and Russia until Poland regained its sovereignty in the wake of World War I.
2Russia is a transcontinental country in eastern Europe and northern Asia. The vast majority of its population (80%) lives in European Russia, therefore Russia as a whole is included as a European country here.