If the results of PC World's second 13-city 3G Wireless Performance Test mean anything, iPhone users will be dancing in the streets of every major city in America.

In PC World’s most recent tests, conducted in December 2009 and January 2010, AT&T’s average download speed increased to 1,410 kbps, or 1.4 mbps. That's up almost 67 percent from AT&T's average download speeds of 818 kbps in tests conducted by PC World last spring. 

The PC World 3G Wireless Performances Tests are done in partnership with Novarum. They test download speeds, upload speeds and network dependability of the AT&T, Sprint, T-Mobile and Verizon 3G networks from 20 locations in each of 13 U.S. cities. PC World says it ran more than 51,000 separate tests covering 850 square miles of wireless cell coverage servicing 7 million wireless subscribers.

AT&T's Ralph de la Vega has publicly conceded on a number of occasions that AT&T's network performance was suffering in major cities like New York and San Francisco. The carrier went so far as to launch an app called "Mark the Spot" that allows customers to report problems with AT&T's network in real time. 

According to Jenny Bridges, a spokeswoman for AT&T, the carrier made significant improvements in 2009. Bridges said AT&T added about 1,900 new cell sites, more than 100,000 new circuits for backhaul and doubled the number of fiber-served cell sites. 

But perhaps the most high-profile improvements were the addition of 850 MHz spectrum in a number of markets, as well as deployment of HSPA 7.2 software at all of AT&T's 3G cell towers nationwide.

"In 2010, we plan to spend between $18 billion and $19 billion in total capital expenditures, a 5 to 10 percent increase over 2009," Bridges said.

The investments are apparently working. In Baltimore, New York City, New Orleans, Portland and Seattle, AT&T’s average download speeds more than doubled. The network’s 13-city average download speed was 1.4 mbps. None of the other major networks registered average download speeds of better than 1 mbps.

To compare these results with Verizon Wireless is inevitable, in light of its never-ending 3G “map wars” with AT&T. Verizon’s 13-city average download speed came in at 877 kbps, down 8 percent from its average of 951 kbps in PC World's test conducted last spring. Verizon’s average download speed decreased in seven of 12 testing cities compared to the figures recorded last spring; and in five of those cities – Chicago, New Orleans, Phoenix, San Jose and Seattle – Verizon’s average dropped by 15 percent or more.

Verizon topped reliability and speed in every major market last spring, but these recent test results suggest that the carrier may not be keeping up with demand in some markets. Additionally, Verizon has only recently gotten heavily into the smartphone game with new Android offerings like the Droid. At the end of 2009, Verizon reported 15 percent of its customers were using smartphones, as compared to AT&T's reports of 40 percent adoption of smartphones by its customers.