Oh yeah, there is no doubt that Wigan are Lancashire's* team as well as Wigan Borough's. When I used to live in that part of the world I used to see folk heading south for the rugby.
But my point was that if a side are successful enough then their catchment area can grow quite some distance outside their home town.
*as in the modern rump county that includes Preston, Burnley and Lancaster but not Wigan
I agree about growth being beyond the town boundary for a successful club, whoever you also need good transport links and a large untapped resource on those links.
Wigan is lucky in its geographical position to be able to take advantage of the infrastructure it sits on, and it sits in the middle of a densely populated area.
here is something I posted in the past regarding populations
St. Helens, Wigan and Warrington have a population of around 120,000 - 150,000 each as a starting point for a fan base.
Wigan Borough alone has a population of 360,000 the whole of Wakefield MBC has a population 320,000, the three South Lancs SL clubs discussed sit in a massive conurbation of some 4 million people that is the most densely populated area outside of London. The more people you have on your door step the more people you are likely to get in through the turnstiles.
Although people will and do travel to games the farther away you get from the population centres the less likely you are to pull in the punters. Saints are on the doorstep of Merseyside and aim towards Liverpool for extra support, Wigan is 12 minutes from Preston by train and they target the area to the North, Warrington looks South and East to Chester and South Manchester. All these areas they target have high populations and no other RL to compete with them.
The Wakefield district has to the North/North West Bradford and Leeds to compete with and those two have that area pretty much stitched up, to the West is Huddersfield, again they will have to compete with an SL club that is growing. East of Knottingly you've got field after field to Hull. The only way out for the Wakefield district clubs is to head South to Barnsley, population 75,000, this gives a net target of something just short of 400,000 as opposed to 4 million.
I'll even be kind and say that nobody from East of the Leigh border is included in the figures, I'll be even kinder and now include Widnes as a team vying for these fans since they are now in SL.
Central Lancashire 350,000
Warrington Borough 200,000
That's 4 clubs sat in an area with no other pro RL clubs sharing a population of 2.4 million or 600,000 each.
Compare that with the 'Calder' trio and I'll throw in Barnsley MBC for good measure.
Wakefield MBC 320,000
Total 550,000 giving them 183,000 each, the four South Lancs clubs have over 3 times more people each to go at.
It is these figures that make it difficult for clubs (amongst other factors), the fact that the clubs are hemmed in to the West and North by other SL clubs who have successfully tapped into these markets that limits what they can do in these areas, to the East is a desert.
Just shear numbers of population make it difficult.
West Yorkshire has a population of 2.2 million divided between something like 10 clubs, even looking at it that way only gives each club a 220,000 target each.
The figures in some ways may be simplistic but they show the crux of the problem.