Reagan is a Republican who cruised to victory in a three-way race for the GOP nomination against state Rep. Justin Pierce and businessman Will Cardon. Democrat Goddard faced no opposition in his primary.
Both have made banning anonymous campaign spending a campaign focus. Goddard has attacked Reagan for supporting a massive election law overhaul that was repealed this year.
The secretary of state is Arizona's top elections officer and becomes governor if there's a midterm vacancy in that office.