Kahului, where my hotel (Maui Seaside) is located is the commercial capital of the island. The governmental capital is Wailuku, which is just to the northwest of Kahului.
As the towns grew they merged more and more, and today there is no real visible boundary between them. In fact, you can find texts that talk about "Kahului/Wailuku" as if those were two names for the same town.
View over a residential district of Kahului. (Wailuku looks the same.)
Driving down Highway 32, "Kaahumanu Avenue", the main street going through Kahului and Wailuku.