Source: Ash, Russell. The Top 10 of Everything, DK Publishing, Inc.: New York (1997), pg. 160-161; Adherents.com. This list of countries is taken directly from the Ash book, except for Indonesia, whose large population of Balinese Hindus were inadvertantly left off of Ash's list.
U.S. States With Highest Proportion of Hindus in the Population, 1990
This data set is from the 1990 National Survey of Religious Identification, conducted by the City University of New York, based on self-identification, as collected through a nationwide phone survey of 113,000 people. Although this is the most extensive survey of it's kind, for a group as sparsely represented as Hindus in the United States, the results presented here may have very little statistical significance. Perhaps the only thing that can be reliably determined from this survey was that in 1990, New York had a higher proportion of Hindus than any other state, New Jersey seemed to be in second place, and in other U.S. states, the Hindu population was undetectable, or nearly so, using a random survey of this kind.
The appearance of Illinois, Maryland, Georgia and Michigan on this list may correspond to known clusters of Hindus in Chicago, Washington, D.C., Atlanta and Detroit. But Colorado, Nebraska and Wyoming are not known from other sources to have particularly high proportions of Hindus. The appearance of these states, as well as the others with "0.2%" may simply be a result of random chance.
Source: Kosmin, Barry A. and Seymour P. Lachman. One Nation Under God: Religion in Contemporary American Society; Harmony Books: New York (1993), pg. 88-93.