Look both ways before you answer today's Geo Quiz.

Motorcycle taxis in Nigeria

Nigeria roads and highways there are notoriously dangerous. Motorcycle taxis called okadas are part of the problem. They go too fast, drivers often don't wear helmets, and they're considered a menace by many motorists. But they're the cheapest way to get around Nigeria's crowded cities.

Motorcycle taxis in Nigeria

We're looking for one of those cities, Nigeria's third largest city in area --- after Lagos and Ibadan. But it's the second most crowded with a population of close to 4 million. We'll tell you about some ingenious efforts by taxi bikers there to get around Nigeria's new motorcycle helmet law.

First name this northern Nigerian city.