Roadtrekers traversing the U.S. will probably end up in Austin, Texas sooner or later.
When you do, be sure not to miss out on one of the country's greatest natural spectacles.
Every night just before sunset, from March to November, hundreds of folks gather along the Congress Avenue bridge (see interactive map below), because the crevices built into the underside of the bridge are home to as many as a million and a half Mexican free-tailed bats.
Many people watch from the bridge, but if you do you'll miss all the early action. Instead, come a little early and get a parking spot at the Austin American-Statesman lot on the south side of the span.
Walk out into the attached park. Take a lawn chair, even a picnic or a beverage if you like. The park also often features displays and information stations staffed by bat experts who can answer your questions. As the sun gets low, you'll see these tiny mammals begin to circle around under the bridge. More and more of them emerge and join the aerial dance as twilight comes on. Then, at one moment, they all swoop out from underneath and head upriver to devour tons of mosquitoes before returning to feed their young.
Sometimes the fly-out takes as long as two hours, so take your time. You can sit for the twenty minutes or so it takes for the parking lot to clear or, for a romantic treat, skip the traffic and take a pedicab from the park. You can enjoy the nighttime lights of the city on your way to one of Austin's many great restaurants. We really like Frank & Angie's Pizza, an old time Italian eatery tucked in the back of a parking lot a few blocks from the bridge.
Austin isn't the only place to see this amazing display, but it's the only city where it happens, and the biggest urban bat colony in the world. If you prefer a more rural setting, further west you can watch a similar departure at Carlsbad Caverns National Park. Wherever you see it, you'll never forget it. Bats are great friends to campers, eating as many as a thousand bugs an hour, so take the time to cheer them on. Happy travels!