(CNN) -- Samoa will switch its driving from the right side to the left side of the road on Monday in a move opponents have called ill-conceived and said will lead to dozens of wrecks and fatalities.



Proponents tout the change, which no other country has attempted since the 1970s, as making economic sense.



Thousands of angry Samoans protested in the streets, and one group -- People Against Switching Sides (PASS) -- unsuccessfully challenged the constitutionality of the change in the country's Supreme Court.



Opponents have also aired nightly ads depicting roadsides littered with crosses and vandalized newly-erected signs warning drivers to "keep left."



Bus drivers have demanded the government compensate them to change the location of passenger door and the steering wheel.



The nation has declared Monday and Tuesday holidays for people to adjust to the change and banned alcohol sales for the next three days.



The government said it will strictly enforce the use of seat belts and has built speed bumps to prevent wrecks.



Until now, most of the cars in the Pacific island nation have been imported from the United States, where drivers travel on the right side, and Samoa's neighbor, American Samoa.



The change will allow the thousands of expatriate Samoans who live in their nation's biggest neighbors, New Zealand and Australia, to send used -- and therefore, cheaper -- cars to their families back home. In both those countries, drivers travel on the left side of the road.



"It narrows the bridge between the rich guys and people like us, the lower class people from the rural areas," Fa'aleaga Young Yen told CNN affiliate TVNZ in New Zealand.  Watch people speak out about the switch »



"Just the freight alone cost me US $3,500 from Hawaii," he said. "To send the same kind of car from New Zealand? NZ$1,400 (US$968)."



About 70 percent of the world's population drive on the right side of the road. But many countries -- primarily those that were once British colonies -- remain to the left.



Many have gradually switched over the years, including Sweden in 1967, Iceland in 1968, Nigeria in 1972 and Ghana in 1974. All have gone from driving on the left side to the right.



Samoa's case seems to be unique because it is steering in the opposite direction.
Which days are declared holidays? Who switched from driving on the left to the right? Which countries switched from driving on left side to the right? Who rejected constitutional challenge to change? What days were declared holidays? What was declared holidays for people to adjust?
Monday and Tuesday Samoa Samoa People Against Switching Sides (PASS) Monday and Tuesday Monday and Tuesday
question: Which days are declared holidays?, answer: Monday and Tuesday | question: Who switched from driving on the left to the right?, answer: Samoa | question: Which countries switched from driving on left side to the right?, answer: Samoa | question: Who rejected constitutional challenge to change?, answer: People Against Switching Sides (PASS) | question: What days were declared holidays?, answer: Monday and Tuesday | question: What was declared holidays for people to adjust?, answer: Monday and Tuesday