Louise A. Mozingo and Christopher B. Leinberger’s related Op-Ed articles chart a sound direction for the United States to rethink sprawl and re-center people and businesses. Urging the construction of livable communities composed of walkable, mixed-use, transit-served neighborhoods is the right focus for a number of reasons.

Unfortunately, decades-old policies and laws discourage sprawl-free developments in much of the country. Local laws are shaped by federal policy. The current national transportation bill continues to focus on highway development at the expense of walking, biking and public transit.

Federal Housing Administration limits on financing of commercial developments essentially cap the mixed-use districts Ms. Mozingo and Mr. Leinberger wrote about. Moreover, the mortgage interest tax deduction continues to support overfinancing of outsized homes in the suburbs.

It’s time that we updated our nation’s policies so that we can begin a new chapter in American metropolitan development. If we continue to use outmoded 20th-century tools to solve 21st-century problems, especially in an age of diminishing public funds and heightened climate and security concerns, we will go nowhere fast.