SAN FRANCISCO (AP) — Google's influential search engine has hit a tipping point in technology's shift to smartphones. More search requests are now being made on mobile devices than on personal computers in the U.S. and many other parts of the world.

The milestone announced at a digital advertising conference Tuesday serves as another reminder of how dramatically online behavior has changed since 2007. That's when Apple released the first iPhone, leading to a wave of similar devices that have made it easier for people to stay connected to the Internet wherever they go.

The upheaval has rocked PC makers and other tech companies such as Microsoft with businesses tied to sales of desktop and laptop computers. Google has been able to adapt better than most companies, partly because its search engine and other services are embedded in the popular Android mobile operating system, but it hasn't been totally unscathed.

Google's average ad prices have been declining for the past three-and-half years, partly because marketers so far have been unwilling to pay as much for the commercial message displayed on the smaller screens of smartphones. The company, though, says mobile ad prices have been steadily climbing and will continue to do so as marketers recognize the value of being able to connect with prospective customers at the precise moment that they are looking for someplace to eat, or comparing products on a smartphone while standing in a store.

"The future of mobile is now," says Jerry Dischler, a Google Inc. vice president in charge of the company's "AdWords" service for creating online marketing campaigns.

Besides in the U.S., Google's mobile search requests are outstripping requests in nine other countries. Japan is the only other country that Google is identifying.

The Mountain View, California, company isn't specifying just how many mobile search requests it is getting. Google processes more than 100 billion search requests worldwide each month, including queries on PCs.

As part of the mobile transition, Google last month overhauled its search-recommendation system to favor websites that are easier to read and load on smartphones. That change, known as "Mobilegeddon," prodded millions of websites to make changes to ensure they work well on smartphones to avoid being demoted in Google's search results.

Google also has been introducing advertising formats that tend to work better on mobile devices. For instance, rooms can now be booked within hotel ads, and car ads can now be swiped across a screen to make it easier to comparison shop.

In addition to announcing the milestone in mobile search, Google also introduced on Tuesday a service for comparing mortgage rates in the U.S. The mortgage product expands upon a similar service for auto insurance policies that Google unveiled in California in March. Google is adding three more states — Texas, Illinois and Pennsylvania — to the auto insurance service.