Train commuters hold on to the front and side of an overcrowded passenger train in Soweto, South Africa.

Passengers sit in a tram during a rush hour in Hong Kong.

People cross the road in the high-density suburbs of Mbare in Harare, Zimbabwe.

North Korean commuters ride on a subway in Pyongyang, North Korea. Foreign visitors are usually only allowed to make one or two stops on Pyongyang's north-south Chollima subway line.

Pedestrians cross the road in the Hong Kong shopping district of Mongkok during rush hour.

Irma Ortiz applies makeup while waiting in line at the Western Hemisphere's busiest border crossing in Tijuana, Mexico. An average of 50,000 cars and 25,000 pedestrians cross daily through the San Ysidro Port of Entry – many waiting for hours on their way to jobs, schools and shopping malls in the U.S.

Commuters climb off a motorized boat during rush hour onto a pier at the Saen Saeb canal in Bangkok, Thailand.

Passengers look at the Sheikh Zayed highway towers from the front window of a remote control metro car during afternoon rush hour in Dubai, United Arab Emirates. The 5-year-old Dubai metro has grown from serving 60,000 passengers daily in 2009 to 500,000 commuters.

The headlights and taillights of moving cars streak past cars waiting their turn at an intersection during the evening rush hour in Sydney, Australia.

Thousands of motor scooters wait at a stoplight during the morning commute in Taipei, Taiwan. There are more than 15 million motorcycles in Taiwan, or 67.6 for every 100 people, according to statistics from Taiwan's 2013 official Directorate General of Budget, Accounting and Statistics.

Cable cars carry people through the fog between La Paz with El Alto, Bolivia. The world's highest cable-car system transports thousands of passengers a day more than 13,000 feet above sea level.

A boy sells coconuts during rush hour in the middle of heavy traffic near an intersection in New Delhi, India.

Commuters get off a free ferry connecting parts of Amsterdam.

In this photo made with a long exposure, lights from evening rush hour traffic move over the San Francisco Oakland Bay Bridge.

Commuters rush into a train garage during a morning rush hour at a subway station in Beijing.

Commuters walk along Manhattan's 34th Street, in New York.

A woman smells her bouquet while walking on the Wilshire Boulevard over the 110 Freeway during evening rush hour in Los Angeles.

Morning commuters ride a water taxi up the Chicago River to Michigan Avenue.

A man stands with other commuters in a crowded metro car during rush hour in Rio de Janeiro.