examination shall be citizens of the United States, (including all
persons born in the United States, and not owing allegiance elsewhere,)
between the ages of eighteen and twenty-five, and shall furnish such
testimonials of personal character and take such oath of allegiance as
the Board shall prescribe: _Provided_, That, if the examination is for
any office the duties of which are to be performed in any particular
State, then the applicant, in addition to the above requirements, shall
have resided in such State one year before the time of examination, and
in such case the Board shall designate a place of examination within
such State: _Provided, however_, That the President may suspend the
operation of the preceding proviso as to any States or parts of States
where he may deem it expedient so to do.