American hop is a term that refers to the hop varieties that are grown and used in the United States for brewing beer. Hops are the flowers of female Humulus lupulus plants, and they provide bitterness, flavor and aroma to beer. Hops also have preservative and antiseptic properties that help prevent spoilage and infection in beer.

The history of American hop dates back to the 17th century, when the first European settlers brought hop rhizomes from England and planted them in the New England colonies. These hops were soon supplemented with wild native hops and crosses between cultivated and wild varieties. The first commercial hop production in the US began in California in 1854, during the Gold Rush period. However, hop production shifted to the Pacific Northwest region in the late 19th century, due to disease outbreaks, prohibition and market changes. Today, Washington, Idaho and Oregon account for about 96% of US hop acreage.

American hop varieties display a wide range of flavor and aroma characteristics, from citrus and floral to piney and resinous. They are generally categorized as bittering, finishing or dual-purpose hops, depending on their alpha acid content and usage in brewing. Alpha acids are the compounds that provide bitterness to beer, while beta acids and essential oils contribute to flavor and aroma. Some of the most popular American hop varieties are:

• Cascade: An aroma hop developed by USDA-ARS in 1956 from Fuggle and Serebrianka (a Russian variety). It has a flowery and spicy, citrus-like quality with a slight grapefruit characteristic. It is widely used in American pale ales and India pale ales.
• Citra: A dual-purpose hop developed by Hop Breeding Company in 2007 from Hallertau Mittelfrüh, Tettnang, Brewer’s Gold and East Kent Golding. It has a strong citrus and tropical fruit profile, with notes of grapefruit, lime, orange, mango and passion fruit. It is often used in American pale ales, India pale ales and wheat beers.
• Simcoe: A dual-purpose hop developed by Yakima Chief Ranches in 2000 from unknown parentage. It has a complex piney, earthy and fruity aroma, with hints of passion fruit, apricot, berry and citrus. It is commonly used in American pale ales, India pale ales and amber ales.
• Columbus: A bittering hop developed by Hopunion LLC in 1990 from unknown parentage. It has a high alpha acid content (14-16%) and a pungent earthy and herbal aroma. It is often used in American pale ales, India pale ales and stouts.
• Amarillo: An aroma hop discovered growing “wild” (spontaneously) in one of their hop yards by Virgil Gamache Farms in the late 20th century. It has a floral, citrusy and orange-like aroma. It is frequently used in American pale ales, India pale ales and wheat beers.

American hop varieties are constantly evolving as new cultivars are developed by breeding programs or discovered by chance. Some of the newer varieties include Azacca, Calypso, Apollo, Mosaic and El Dorado. Each variety has its own unique characteristics that can enhance the flavor and aroma of different beer styles.

American hop is an essential ingredient for many craft brewers who want to create distinctive beers with complex profiles. By choosing the right variety and amount of American hop for each recipe, brewers can achieve different levels of bitterness, flavor and aroma that suit their preferences and goals.