This street is named for Dexter Horton (1825–1904). Born in Seneca Lake, New York, he was living in Princeton, Illinois before he came west in 1852 with, among others, Thomas Mercer and Daniel and Clarence Bagley. He and Mercer came to Seattle in 1853. In 1870, he founded the city’s first bank, the Dexter Horton Bank. (It later merged with Seattle National Bank and First National Bank to form the First Seattle Dexter Horton National Bank, which unwieldy name became First National Bank of Seattle, then Seattle-First National Bank, and eventually Seafirst, the name it used from 1974 until the brand was retired in favor of Bank of America in 1999. (Bank of America had bought Seafirst in 1983.)
Dexter Avenue begins just south of Denny Way at 7th Avenue and becomes Dexter Avenue N north of Denny. From there it goes 2 miles north, then northwest, to the intersection of Westlake Avenue N, 4th Avenue N, and Nickerson Street, just south of the Fremont Bridge.