It’s official. Atlanta had the highest U.S. growth rate for Facebook users in 2009.

iStrategyLabs, the digital marketing firm which has been tracking Facebook’s growth since October 2007, reported that the Atlanta area had a 267.6% increase between Jan. 4, 2009,  and last Monday. We blogged in July about Atlanta’s phenomenal growth, noting that the metro area had jumped to No. 2 in registered users behind only New York. However, Los Angeles, which experienced its own 240.6% growth, surged to No. 2 over the second half of the year.

Atlanta, as of Jan. 4, had 1,967,720 registered Facebook users, compared to New York’s 2,934,580 and L.A.’s 2,166,840. Atlanta slightly edged Chicago. (See full chart here.)

One can quibble about the value of numbers, especially if accounts are inactive, but if you own a business in metro Atlanta, one point should be clear: Your customers are on Facebook. And while the demographics aren’t broken down for Atlanta, growth is strongest nationally in the 25-34, 35-54 and, especially, 55-plus markets. Sounds like your customers, right?

Facebook provides a unique opportunity for Atlanta area businesses to connect with customers and potential new ones. Don’t know where to start? Don’t have time for Facebook? There are plenty of qualified consultants or marketing firms who can help.

Strike now while it’s hot.