We read a little blurb in New York Magazine about the different types of grapes showing up in the greenmarkets, and we realized that we don't think about special varieties of grapes the same way we do apples or pears. They all kind of look the same...
There were three varieties mentioned in the (very) brief article (you can see it here) that are largely grown in New York State, so we dug up a few details about each.
Concord: These bluish purple, full-bodied grapes were first grown in Concord, Mass., but New York is now second (behind Washington state) in production. In 1869, Thomas Bramwell Welch (sound familiar?) pressed this grape into unfermented juice. It's still the base of Welch's grape juice.
Niagara: This variety was created in Niagara County, NY, in 1868 and is considered the white-skinned counterpart to Concord. It is also used in juice, mostly white grape juice (including Welch's). Niagaras are pale green, sweet, and aromatic. They don't travel well, so you rarely see them far from where they're grown.
Himrod: These pale, yellowish green grapes are small and seedless. They were created in Geneva, New York as part of the Cornell University grape breeding program in 1952. Himrods grow in large, bountiful clusters and have a sweet, honey-like flavor.