In the 1810s, a pork and beef business was the principal industry.

The area's principal industry is tourism, in particular whale watching.

Timber was the principal industry of the area until the 1860s.

Salt manufacture has remained the principal industry for the past 2,000 years.

It has become the principal national industry & the reason for a cautious liberalization.

For many years coal mining was the principal industry in the area.

Today, catching fish remains the principal industry, although tourism has become important as well.

Watchmaking was for many years the principal industry of the region.

Together, they saw what a bid could mean to the area's principal industry, tourism.

"And what does the Net say is this city's principal industry?"