For the price of one mile of freeway you can have an entire bike-friendly city

For one thing, there's money. Cars are a major source of household debt – and unlike other investments like houses, they depreciate, costing more the longer you own them and the more you use them. For most US families, car ownership is one of those damned-either-way propositions. According to the federal Consumer Expenditure Survey for 2012, the average US family of four spends about $10,000 a year on transportation – more than they spend on food. This isn't reasonable or affordable. But the alternative can be far worse, depending on where you live, work, send your kids to school, school, shop, get healthcare, go to church, and all the other things we do in our daily lives.

Then there's the cost of roads – building and maintaining them. Our gas taxes cover this, is the myth. Unfortunately, this hasn't been true since 1956, when President Eisenhower signed the Interstate Highway Act, consigning us to generations of escalating civic and private debt. (This report is a great primer on the topic.) Nowadays, about half the cost of the country's road system is paid for through gas taxes; the rest comes out of the general fund. The other half is paid for through taxes – sales, income, property, special levies – which means that we all pay for roads, whether or not we actually drive on them.

Bikes, by contrast, are a bargain for taxpayers and users alike. For a few thousand gallons of paint and a bit of signage and concrete, you can get yourself a bike-friendly city – and tens of thousands of smiling riders to go with it. It's been famously said (and fact-checked) that Portland's entire bicycle system, the one that makes us the most bike-friendly city in this country, the one that makes us one of the healthiest cities in the country and that has cushioned a few of the blows of the recent recession, has cost about $60m over the years. That's the same cost as – wait for it – one single mile of urban freeway.