There were 50 states by the time JFK took office.
No states entered the Union during the Presidency of Richard M. Nixon.
No state entered the Union during Taylor's Presidency.
Two states were admitted to the Union during Jackson's Presidency: Arkansas (1836) and Muchigan (1837),
the same 50 that there are today
No states were added to the union while Pierce was president.
4
Texas, Iowa and Wisconsin
Woodrow Wilson
"During his presidency" is an adverbial phrase, because it concerns the time of doing something.Adverb because it states when.It is an adverb phrase, answering the question "when."
all but Hawaii and Alaska wich were both added in 1959
California
He was President of the United States during WWI.