A nuclear-cut canal would loosen carrier size limits

How would history change if Project Plowshare created a new canal across the Isthmus of Tehuantepec in 1960?

It would remove a major dimensional constraint on US carriers and might encourage much larger warships and further nuclear-excavated canals, at severe radiological cost.

The counterfactual assumes Project Plowshare uses nuclear explosives to cut a canal across the Isthmus of Tehuantepec in 1960. Its naval argument depends on the new route being wide enough to remove transit restrictions associated with the Panama Canal, while the answer also warns about radiation. Avoiding a voyage around South America could then encourage larger American supercarriers. One possibility is to retain air groups above one hundred aircraft; another is to use the additional hangar space for larger strike aircraft while keeping roughly the same aircraft count. The A-5 Vigilante or a successor is suggested as a possible beneficiary with a longer service career. These are conditional design consequences of the imagined canal, not an account of a completed project.