Across the world, urban populations keep swelling. The increase in people commuting to cities is clogging up freeways, and most of the cars taking space up on roads are singe-occupancy vehicles. To fix the problem in the San Francisco Bay Area, a nonprofit has come up with a bill that could also be implemented across cities worldwide. The bill would enact a city-wide “trip cap” to limit the number of car trips through the region; companies within the city would be permitted a certain number of commuter vehicles depending on their size, and the companies that exceed the number would have to adopt the commute-reducing strategies outlined in the bill. With a plan like this, the number single-occupancy vehicles on the roads could drop from 75 percent to 50 percent.