If the area was a major commercial shipping hub once, what's the reason it isn't any more? Depopulation? (If it's depopulation, then was it emigration or was it a fall in birth rates?)
I'd assume it's just good ol' deindustrialization.
From Wikipedia:
> The town is at the junction of the Forth and Clyde and Union Canals, a location which proved key to its growth as a centre of heavy industry during the Industrial Revolution. In the eighteenth and nineteenth centuries, Falkirk was at the centre of the iron and steel industry, underpinned by the Carron Company in nearby Carron. The company made very many different items, from flat irons to kitchen ranges to fireplaces to benches to railings and many other items, but also carronades for the Royal Navy and, later, manufactured pillar boxes and phone boxes. Within the last fifty years, heavy industry has waned, and the economy relies increasingly on retail and tourism.
So, yes, deindustrialization. But being at a key canal junction doesn't mean much today, since modern railroads and steamships rendered the canals obsolete a century-ish ago.
The canals are too small for goods (and a lot of hastle opening/closing locks) - the road and rail networks are way faster.