Overview. If you frequently experience shortness of breath or you hear a whistling or wheezy sound in your chest when you breathe, you may have asthma â a chronic condition that causes inflammation and narrowing of the bronchial tubes, the passageways that allow air to enter and leave the lungs.
1 At 47,958 kilometres (29,800 miles) in total length, the Pan-American Highway is the longest road in the world.  The road starts in Alaska, North America and ends in the lower reaches of South America.
As a travel writer, I was eager to follow one route complete across the USA and write a guidebook to this historic road. Initially, I typed âLongest Road In the USAâ into Google, and up popped âUS Route 6â as second only to US Route 20. Route 6 was truncated in 1964 â it now officially ends in Bishop, CA and is currently 3,205 miles long. But it was once the longest American highway, and is still the longest CONTIGUOUS highway, as Route 20 breaks up through Yellowstone National Park.