Members of Clan Hay immigrated to America and made significant contributions to the nation's development. They played pivotal roles as military leaders during the Revolutionary War and were instrumental in the westward expansion. Today, descendants of Clan Hay continue to impact American society.

In Virginia, the town of Hayes was named in honor of Lt. Hugh Hayes.

In the United States, variations of the surname Hay include Hays and Hayes. These variations arose due to phonetic spelling conventions and limitations in literacy during the periods of immigration and settlement.

Following the Revolutionary War, descendants of Clan Hay predominantly moved south, settling in Tennessee. Notable figures from this lineage include Governor William Hall (Elizabeth Cage, daughter of William Cage IV and Ann Hall, is the niece of Tennessee Governor William Hall and she went on to marry Harmon Atkins Hays), President Andrew Jackson (connected through marriage to Rachel Donelson, whose sister Jane Donelson married Col. Robert Hays), President James K. Polk (whose sister married Dr. John B. Hayes), and John "Coffee" Hays (from Wilson County), who led the Texas Rangers and was the first to use the Colt revolver in battle, facilitating westward expansion.

President Jackson named his property Hermitage in honor of his brother-in-law and friend, John Hermitage Hays, which also gave rise to the name of Hermitage, Tennessee.

Donelson, Tennessee, is named after the Donelson family.

Rutherford Birchard Hayes was an American military officer, lawyer, and politician who served as the 19th president of the United States from 1877 to 1881. As an attorney in Ohio, Hayes served as Cincinnati's city solicitor from 1858 to 1861.

Numerous locations across the country are named in honor of the Hays/Hayes family. Haysborough (established in 1784, also known as Haysboro) and Hays Station (established in 1781, located in present-day Nashville) are two examples. Hays Station was founded by Nathaniel Hays and Samuel Hays.

Haysboro was established by Col. Robert Hays in 1786. Col. Hays married Jane Donelson, the sister of Rachel Donelson, Andrew Jackson's wife. Samuel Jackson Hays, born to Robert and Jane in 1804, was killed by Native Americans in 1793 near Hays Station.

Nathaniel Hays sold land to Andrew Jackson, which became Jackson’s Hermitage. Consequently, the original Hays Station ceased to exist as a separate entity.

The city of Hays and Fort Hays were named after Major General Alexander Hays, a Union general who was killed at the Battle of the Wilderness during the Civil War. The original Fort Hays, located south of Victoria, was relocated in June 1867 following a flood. Hays City was established on November 23, 1867.

John Coffee Hays, born at Little Cedar Lick, Wilson County, Tennessee, was named after his relative by marriage, Colonel John Coffee. In 1836, at the age of 19, he moved to the Republic of Texas. Appointed to a company of Texas Rangers by Sam Houston—whom he knew from Tennessee—Hays received a letter of recommendation from his great-uncle, President Andrew Jackson.

Hays led the Rangers in campaigns against the Comanche and played a crucial role in the Battle of Plum Creek in 1840, alongside Tonkawa Chief Placido and his scouts. He also commanded forces during the Mexican–American War (1846–1848), supporting President James K. Polk’s westward expansion agenda. John Coffee Hays’ great-aunt-in-law, Ophelia Hayes, was the sister of President Polk.

Hays County, Texas, is named in honor of John Coffee Hays for his leadership in the Texas Rangers and his contributions to the Mexican-American War.