Ms. Le Pen was strongest in areas with high unemployment and low wages, where she campaigned on pledges to stop immigration and renegotiate France’s relationship with the European Union.
But Mr. Macron, a political newcomer who campaigned on a centrist, pro-Europe platform, gained widespread support from voters who rejected him in the first round. The vote preserved a French political tradition of mainstream parties working together to bar candidates from the far right, known as the Republican Front. Many voters said they saw him as the lesser of two evils.