"Aircraft Carrier Number 1" Topic

One hundred years ago, the U.S. Navy embarked on a revolutionary and innovative journey with the commissioning of its first carrier, the USS Langley.

USNI: link

Britain led the way.

link

and sunk on 27 February 1942 on a hopeless mission to supply aircraft and crews for the defense of Java.

Now let's keep things positive. There is enough negative in the news.

IIRC balloons are, by many definitions, 'aircraft,'
although flight characteristics are very limited.

If we accept that, the first US 'aircraft carrier'
might have been the 'George Washington Parke Custis,'
a coal barge converted by the Union to carry balloons
and do recon inland from waterways.

The second, Confederate, may have been the CSS Teaser, a
gunboat fitted to carry a single balloon for recon
purposes.

If we accept the idea that an aircraft carrier is something that wheeled aircraft can take off from and land on at sea then, by my reconning, Langley was the 4th.
By the time Langley commissioned, the RN had already commissioned Furious, Argus and Vindictive, whilst Hermes and Eagle were fitting out.

The USN were certainly fast learners and ambitious though, given that their 2nd an 3rd carriers were Lexington and Saratoga!

Lex and Sara were laid-down as, IIRC, battlecruisers
and, because of treaty limits on tonnage of capital
ships, completed as carriers, which had no limit.

AIUI the USN naming convention for carriers, CV, stands for "Carrier heaVier than Air". It's also why naval air squadron numbers always started with a V. VF-1 was "1st heaVier than air Fighter [squadron]".

While there may have been balloon-carrying ships before Langley, and while the balloons may have technically been aircraft, they weren't lighter-than-aircraft and hence the ships weren't CVs.

Aircraft carriers were governed by the Washington Naval Treaty – there was an overall tonnage limit plus a limit to individual vessel sizes. Carriers under 10,000 tons didn't count towards the tonnage limit; carriers over 10,000 did, and could not be more than 27,000 tons, or 33,000 if converted from an existing non-carrier hull (you were allowed two).

This is how the USN ended up with Sara and Lex and the IJN with Kaga and Akagi, although the former was a bit of a lemon. The IJN intended to convert two battlecruisers but one was damaged in an earthquake so they completed a battleship as one instead. Kaga's 28 knots battleship speed was marginal for a fleet CV by 1941. AIUI she struggled to get 4.1-tonne Kates airborne on occasion, and had she survived till 1943, could probably not have operated Jills (5.5 tons), or Graces (6.5 tons) at all.