As of July 2014, the cost of a first-class stamp on domestic U.S. mail for letters is 49 cents. One stamp marked "Forever" on a letter is sufficient postage to send a letter from California to the White House in Washington in roughly three days from the time the letter is postmarked. For faster delivery, the U.S. Postal Service offers Priority Mail Express service to overnight the letter for $13.09.
The number of stamps needed depends upon the value of each individual stamp. One Forever stamp is for first-class mail up to 1 ounce. Each additional ounce up to 13 ounces costs 21 cents, so if the letter weighs 3 ounces, it costs 91 cents. The postal service sells stamps in values as low as 1 cent and as high as $10. Any combination of stamps to equal the first-class rate is sufficient for a letter, provided the stamps do not hinder the address on the front.
Priority Mail Express costs more than $13. This would take more than 26 Forever stamps, three $5 stamps, a $10 with a $5 stamp, or any combination of stamp values equaling $13.09.
The White House receives postal mail at 1600 Pennsylvania Ave. NW, Washington, DC, 20500. The White House encourages citizens to send the president an email for the fastest method of communication.