Well, the longest time I've heard of for a racing pigeon to take to get home was 8 years (they can live to 12 years or more). He didn't say where he'd been.

Lockheed Aircraft was, not so many years ago, using pigeons to get microfilm from Burbank to Santa Barbara during rush hour (even then, the Ventura freeway was pretty slow during the late afternoon). A truck would bring fresh pigeons down during the night after traffic had cleared up.

The Swiss army retired their pigeon corps about three years ago.