Frontier Forts – I Forts
Iaqua Camp, California – In Humboldt County.
Iberville Fort at Louisianna – On Mississippi River.
Ignatius Fort, Michigan – On Mackinac Island.
Ilges Camp, Arizona – On Rio Verde.
Illinois Fort, Illinois.
Independence Fort, California – On Oak Creek, in Owens River Valley.
Independence Fort, Massachusetts – On Castle Island, Boston Harbor.
Independence Fort, New York – On Hudson River, near Peekskill.
Independence Fort. New York – On Tetards Hill, between Kings Bridge and Yonkers.
Independence Fort, Vermont – Opposite Ticonderoga
Independent Battery, New York – At New York City.
Indian Fort, Montana – On Missouri River, opposite mouth of the Porcupine.
Indian Fort, New York.
Indian Fort, Rhode Island – At Kingston.
Indianapolis Arsenal, Indiana – At Indianapolis.
Indian Fort, Maryland.
Indian Head Battery at Maryland – Twenty-five miles below Washington, on Potomac River.
Indiana State Soldiers’ Home – At Lafayette.
Industry Fort, Ohio – At Toledo.
Infantry Camp, Arizona – Name changed to Camp Pinal.
Inge Fort, Texas – On Leone River, in Uvalde County.
Ingersoll, Fort, Alabama
Ingersoll, Fort, Georgia
Ingoldsby Fort, New York – On Hudson River, in Saratoga County.
Iowa State Soldiers’ Home – At Marshalltown.
Ira Harris General Hospital, New York – At Albany.
Ira Harris Battery, Virginia – On Warwick River.
Iredell, Fort, North Carolina – In Iredell County.
Irish’s Redoubt, Rhode Island.
Iron Banks Batteries at Kentucky – On Mississippi River, 8 miles above Columbus.
Irondequoit Fort, New York – Lake Ontario, at mouth of Irondequoit Bay.
Ironsides Camp, New York – On Staten Island.
Iroquois Fort, New York.
Isabel Point Fort at Texas – Fort Polk.
Island Fort, Rhode Island – In Newport Harbor.
Island No. 10 Batteries on, Kentucky – On Mississippi River; contained eleven earthworks.
Island Point Fort at New York – On Lake Champlain.
Islington General Hospital, Pennsylvania – At Philadelphia.
Ives Camp, Texas – Four miles from Camp Verde.
Izard Fort, Florida – On Withlacoochee River.