4 U.S.C.
United States Code, 2014 Edition
Title 4 - FLAG AND SEAL, SEAT OF GOVERNMENT, AND THE STATES
CHAPTER 1 - THE FLAG
Sec. 2 - Same; additional stars
From the U.S. Government Publishing Office, www.gpo.gov

§2. Same; additional stars

On the admission of a new State into the Union one star shall be added to the union of the flag; and such addition shall take effect on the fourth day of July then next succeeding such admission.

(July 30, 1947, ch. 389, 61 Stat. 642.)