A letter weighing 1 ounce or less sent from California to Virginia through the United States Postal Service costs 49 cents as of January 2014. Each additional ounce is 21 cents. For example, a 2-ounce letter costs 70 cents to mail.
The USPS uses a flat rate for letters mailed within the United States. A letter mailed across town costs the same as one mailed across the country. The cost of metered mail is one cent less than the retail rate, 48 cents instead of 49 cents. Postcards cost 34 cents to mail anywhere within the United States. One-ounce envelopes cost 98 cents to mail, with every added ounce costing an additional 21 cents.