The original Atlantic was built by its inventor, Phineas Davis, and was not preserved. Nicknamed the "Grasshopper" for its unique vertical piston movement, the B&O continued to build around twenty of these locomotives of this same basic design in their Mt. Clare Shops in Baltimore, Maryland, (now home to the B & O Railroad Museum). Three of these historic "Grasshopper" locomotives are preserved and on public display appropriately enough in Baltimore and Ohio. These are the oldest American Built Steam Locomotives surviving today. 4
Baltimore & Ohio Steam Locomotive #7, the Andrew Jackson, which was built in 1836. It was rebuilt and re-lettered as the Atlantic in 1892 when it went on display at the World's Columbian Exhibition in Chicago. Since the original Atlantic had been scrapped, the #7 was modified and backdated to represent the original B&O Steam Locomotive the Atlantic, which it has done at various locations since 1892, up to to the present day. 2
B&O Railroad Locomotive #6, the "John Quincy Adams" which was built in 1835.
This locomotive is on display at the Carillon Historical Park in Dayton Ohio. The Carillon Park was developed by Edward Deeds who acquired the locomotive from the B&O Railroad in the 1940s. It's been on display at the Carillon Park since 1950. 3
This locomotive is displayed at the Carillon Park as “B&O #1” which is the number that it was given since it represents the oldest surviving Baltimore & Ohio Railroad Steam Locomotive.
1- http://www.borail.org/John-Hancock.aspx
2- http://www.borail.org/BO-Atlantic.aspx
3- http://thedaytonmagazine.com/DM/Articles/Dayton_History_5716.aspx
4- http://www.borail.org/The-Mt-Clare-Shops-Historic-Site-and-Buildings.aspx