2003: more than half of Americans have cellphones

The cellular population exceeded half of the number of men, women and children living in the United States for the first time at the end of June 2003, when the penetration rate hit 50.9 percent.

The cellular penetration rate at the end of June 2007 hit 80.5 percent of the 302.2 million US resident population. That’s up from 73.4 percent at the end of June 2006, 65.6 percent at the end of June 2005, and 57.7 percent at the end of June 2004. (info from CTIA-The Wireless Association)