While two-thirds of Apple's (NASDAQ:AAPL) revenue now comes from international markets, that doesn't mean the party's over back home. Developed markets like the U.S. do have greater smartphone saturation than emerging markets, but there are still plenty of potential first-time smartphone buyers to go after. Domestically, 30% of mobile phone buyers have yet to buy their first smartphones. At the same time, Apple generates reliable recurring revenue from a constant string of upgrades and replacements. In the following slideshow, there are four charts that illustrate just how much opportunity Apple still has in the United States.

Evan Niu, CFA, owns shares of Apple. The Motley Fool recommends and owns shares of Apple. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.