1894 Income Tax Form 365	Individual Return - Predates XVI Amendment US Constitution /Post Civil War
1894 Income Tax Form 366	Corporate Return - This form reflects the corporate income tax law that was declared unconstitutional and forced the passage of the XVI Amendment US Constitution
1913 Income Tax Form 1040	Individual Return - This form was purchased from a magazine over 20 years ago and .was advertised as the "original" income tax return.
1913 Income Tax Form 1040	Individual Return - Another variation of a 1913 Income Tax Return from Black on Income Taxes published circa 1915.  For the first several years, forms were privately printed by various companies to a loose standard.
1919 Income Tax Form 1040	Individual Return - Post World War I.  The forms are beginning to look modern.