I pledge allegiance to the Flag
of the United States of America,
and to the Republic
for which it stands,
one nation
under God,
indivisible,
with liberty
and justice
for all.

The American's Creed was written in 1917 by William Tyler Page and adopted by the U.S. House of Representatives the next year (much like the Pledge of Allegiance, the American's Creed reflects the American nationalism that became popular after the Civil War):

“I believe in the United States of America, as a government of the people, by the people, for the people; whose just powers are derived from the consent of the governed; a democracy in a republic; a sovereign nation of many sovereign states; a perfect union, one and inseparable; established upon those principals of freedom, equality, justice, and humanity for which American patriots sacrificed their lives and fortunes.”

“I there fore believe it is my duty to my country to love it, to support its Constitution, to obey its laws, to respect its flag, and to defend it against all enemies.”

Source:

USA Illustration by Erin (Creative Commons License)
Songs-Oaths: Pledge of Allegiance: Ben's Guide to US Gov
American's Creed: Wikipedia

Links:

The Pledge of Allegiance: The flag of the United States