Why the historical treaty gave America no Lexington battlecruiser

Why was the United States not allowed to complete at least one Lexington battlecruiser when Britain retained Hood and Japan retained the Kongōs?

American negotiators treated Hood as equivalent value to a Colorado, while a 42,000-ton Lexington would have exceeded the treaty's ordinary 35,000-ton capital-ship ceiling.

The exchange distinguishes negotiated fleet value from a simple ship-for-ship entitlement. The United States received the Colorado programme while Britain received Nelson and Rodney, preserving the agreed parity in heavy-gun ships. Completing a Lexington as a battlecruiser would have required a special displacement exception comparable to Hood's official 41,000-ton figure. The treaty instead used Lexington and Saratoga as carrier conversions, where official displacement declarations and conversion rules created a different accounting path.