Unfortunately in the US, bike paths have often tended to occur not because of sustainable planning for bicycles, but because people have tended to favor gas-guzzling cars over railways, the railway tracks fall into disuse and abandonment, and then get paved over as bike paths.<p>What would be much nicer for the environment is having both railway AND bicycles. Trains and bikes complement each other amazingly well; in much of northern Europe this combination is a perfect way to get around.<p>Having bikes and no trains sucks because you can't just cram bikes onto buses and cars, so bicycling becomes a hobby exclusively for the athletically fit who are determined to cycle long distances and carry repair tools wherever they go.<p>Having trains and no bikes sucks because once you get off the train you can't get where you need to.