I found myself thinking back to that topic because for the past two or three weeks every time I leave or enter my apartment building, I pass a mountain of unclaimed yellow books in my foyer. Out of all the residents in my building, one lone duck opened up the wrapping and actually took one. A single used book with the rest just sitting there getting dirty and taking up space. So in addition to being a daily eyesore, it's a stark reminder to me how much less we rely on the Yellow Pages and other printed directories.

In her comment, Paula argued that the Yellow Pages allow her to get ideas, see additional information, and other benefits. I can't argue with them, but local search allows you to do that, too -- and given technology's ability to target and create a dynamic experience it just does this better.

And over the last year, I think the local digital directories and engines have made vast improvements to local search functionality, ranging from improved recommendations, enhanced filters, expanded listings, better visual results displays, and improved map integration. Digitized local content also has the power of community, with direct links to consumer reviews, feedback, tips, and other peer-driven information that you can't get (or keep fresh) in a printed directory.

Just look at the empirical data and you can see how much behavior is changing, with our use of the fat yellow book moving to other access points.

One particular access point is mobile. According to comScore, over 35 million users accessed local content via mobile devices in September 2009 with 23 million of the users accessing through a mobile browser, 14 million through a downloaded application, and 9 million using SMS functionality. Out of this, local apps are the fastest growing area (+110% from September 2008 to 2009).

To give some additional perspective, here's a breakdown of growth in mobile-based local access:

While mobile still has a long way to go in terms of sheer volume, the aforementioned is promising, because if Web-based search has taught us anything, we know that search is a key access point for consumers to find content. Some additional comScore data also shows how consumer reliance on mobile search is growing.

These numbers just represent mobile-browser-based searches, because that's all comScore can track right now. So this excludes SMS search like GOOG and 4INFO as well as search apps like Bing for iPhone and BlackBerry users. Search functionality is a key feature in many of the local specific apps -- so while we can't yet quantify all the search activity, we know mobile-based local search is involved and growing.

As for Web-based local search, 10.4% of Web searches are local as of November 2009, which adds up to 2.3 billion local searchers. The growth appears to shrink year over year -- but not because local search isn't growing. Web-based local search grew 8.8% YOY, so local search growth only looks to be slowing because traditional searching is growing faster (23%). While the growth in local and non-local searches vary, the percentage of growth in searchers is much closer (4.4% and 5.7% YOY respectively), meaning that adoption of local search is growing, but searchers are conducting less searches.

Mobile may not have the scale of Web-based local search yet, but our reliance on search to find content and the growing use of mobile devices to access content continues to drive a fundamental shift in behavior that is changing how we access local information. Local search and digital localized content, mobile or not, have improved the ability to keep information fresh, and enhanced the overall experience. This means the printed yellow book will only continue to decline and pile up on our doorsteps, while the use of search to access local content will continue to grow.