10 Most Likely Places to Lose Your Cellphone . / Credit: Smartphone Image via Shutterstock

Next time you're in a coffee shop, you better keep a close eye on your cellphone.

A study by mobile security firm Lookout has revealed that coffee shops were the most likely spot for Americans to have their cellphone lost or stolen in 2011. Other top 10 problematic areas:

  • Bars
  • Offices
  • Restaurants
  • Apartments and condominiums
  • Grocery stores
  • Gas stations
  • Residential
  • Pharmacies or drugstores
  • Parks

Overall, Americans lose their mobile phones about once a year, the study found – a reality that could cost U.S. consumers more than $30 billion in replacement costs this year.

"Each day, $7 million worth of phones are lost by Lookout users alone, and if unrecovered, it would take a significant toll not only on our wallets, but on our psyche too," said Kevin Mahaffey, co-founder and chief technology officer of Lookout.

[You're Calling from Where? What People Do with their Phones in the Bathroom]

Residents of some cities are more prone to losses than others. Philadelphians lose their phone two times more than New York City dwellers, while those in San Francisco and New York lose their phones three times more than Chicagoans.

The top 10 cities in the U.S. for phone loss during 2011 were:

  • Philadelphia
  • Seattle
  • Oakland, Calif.
  • Long Beach, Calif. 
  • Newark, N.J.
  • Detroit
  • Cleveland
  • Baltimore
  • New York
  • Boston

Lookout’s Mobile Lost and Found study was based on the number of phone “locates” performed by the company's 15 million global users in 2011. The study used data from Foursquare to determine popular venues for lost phones in cities across the globe, noting the venue type closest to the lost phone’s location.

Chad Brooks is a Chicago-based freelance business and technology writer who has worked in public relations and spent 10 years as a newspaper reporter. You can reach him at chadgbrooks@gmail.com or follow him on Twitter @cbrooks76.