The Bronze was first admitted in to the American Poultry Association's Standard of Perfection in 1874. Later, beginning in the late 18th and early 19th centuries, some Bronze turkeys were selected for exponentially larger size. These much bigger bird became known as the Broad Breasted Bronze, to differentiate it from the original type of bird which was bred to the Standard of Perfection, and was henceforth called the Standard (or Unimproved) Bronze.
The names of the two varieties are etymologically based in their body types, and they can be principally be differentiated by the Broad Breasted's visibly larger breast size. The plumage of the Standard Bronze is usually lighter and more lustrous than that of of the Broad Breasted. Both have a brown color which is highlighted by shades of copper and blue-green.
The Broad Breasted Bronze went on to dominate the commercial turkey industry for twenty years after its creation, until the Broad Breasted White became the breed of choice. Due to their size, they have lost the ability to mate naturally, and Broad Breasted Bronzes in existence today are entirely the result of artificial insemination. Having retained the ability to reproduce (among other traits), the Standard Bronze is considered to be a variety of heritage turkey.
Today, both the Standard and Broad Breasted Bronze turkeys are listed on the ALBC's conservation priority list. The Standard is listed as "Critical", but the exact numbers of Broad Breasted is currently unclear. Standard Bronzes have additionally been included in Slow Food USA's Ark of Taste, a catalogue of heritage foods in danger of extinction.