From Marketplace:

Even if voters are already entrenched in their positions on the presidential race, there are other races that matter on ballots this year. Jonathan Bydlak at the R Street Institute points to congressional, state and local races where many voters still might not know who some of the candidates are.

“If we’re talking about the presidential specifically, it is true that there are fewer undecided [voters],” said Bydlack, but “in the context of a congressional election … you may not have that same level of name recognition.”