This island is a microcosm in many ways, small but not tiny. The following statistics are intended to convey a sense the actual scale of the island.
Kauaʻi is a county (the privately owned Niʻihau included) within the state of Hawaii. At the library I found a report that provides a lot of statistics that paint a clear if sometimes surprising picture of this place. Here are some excepts from the 2010 data in the report.
The island of Kauaʻi is 552.3 square miles, with 113 miles of coastline, the fourth largest island in the state. Niʻihau is 69.5 square miles with 90 miles of coastline, twenty miles away.
The population in 2010 census is 67,000, with on average nearly 20,000 visitors (tourists) on island. Nearly one millions visitors arrive per year
Of the resident population, haole (whites) are the dominant ethnic group at 32%, followed by Hawaiian/Polynesian at 20%, Filipino 19%, Japanese 18%, and others for the remaining 11%.
Just over 1% of the population here is homeless, excluding the so-called "hidden homeless" (living with family or friends).
Broadband Internet access (as of 2010) was 59% with 83% having home access. Access is lowest among the older (65 and older) and in the west (where I am staying now).
Electricity here is, I believe, the most expensive in the nation at over $0.40/kWh. The electricity I am consuming is generated at Port Allen by KIUC from burning oil shipped from the mainland by tanker.
Source: "Measuring What Matters for Kauaʻi" [Part I and Part II] by the Kauaʻi Planning & Action Alliance