The last transmission
The last message Earhart sent to the USCGC Italia was “We are running on line north and south.” It indicated that Amelia believed she has reached her destination’s charted position – Howland’s Island. But she was wrong.
Source: OMG Check It Out
Although the USCGC Itasca’s attempts to communicate with Earhart were unsuccessful, they were able to alert the US Navy. The US Navy were unable to find any traces of the plane or Earhart and Noonan in Howland’s Island.
Gardner Island
The USS Colorado was eventually sent off from Hawaii to help with the search for the celebrity aviator. Naval aircraft flew over several islands in the area hoping that they will be able to find a clue as to where Amelia landed.
Source: OMG Check It Out
Gardner Island happened to be one of the many islands covered in the search area. It has been known to be uninhabited for decades. But the USS Colorado sees that it would have been the perfect size for a plane to land and decided to search there as well.