Towns sitting on a national border develop a distinctive doubled character, and it is visible in the shops, the signage and the traffic. The pattern follows directly from what a border does.
A border creates a price step
Taxes, duties, wages and regulation change abruptly at a frontier, so identical goods can cost noticeably different amounts within a few hundred metres.
Wherever that gap is large enough to justify the journey, trade forms across it, and the businesses serving that trade cluster immediately on the cheaper side.
Fuel, alcohol, tobacco, pharmacy goods and groceries are the classic categories, because they are bought regularly and the differentials are consistent.
The flow can run both ways at once
Border towns often send shoppers in one direction for one category and receive them from the other for a different one, because the differentials are not uniform.
Fuel may be cheaper on one side while dentistry, haircuts and restaurant meals are cheaper on the other, producing two overlapping streams of traffic.
This is why a frontier town supports more retail and services than its population would suggest, and why the shops on each side look quite different.
Labour crosses as well as goods
Wage differences pull workers across a border daily, which produces a commuting pattern with its own rush hours and a service economy built around it.
Housing costs then diverge in the opposite direction, since people earning on the higher-wage side often live on the cheaper one.
Those flows are what make the town genuinely bilingual in practice rather than merely on signage, because the working population uses both languages daily.
Currency and payment habits double up
Where the two sides use different currencies, businesses near the line commonly accept both, applying their own exchange rate at the till.
That convenience carries a cost, and the rate offered at a shop counter is generally less favourable than a card transaction or a bank exchange.
Travellers benefit from knowing which side of the border they are actually paying on, since the same purchase can be priced differently depending on the currency used.
What changes when the border does
Border towns are unusually sensitive to policy, and a change in customs arrangements or checks can alter the local economy within months.
Tightened controls suppress casual crossing first, which hits the small retailers whose business depends on people making a short trip without much thought.
Because rules on customs allowances, identity documents and permitted goods differ by frontier and change over time, checking current requirements for the specific crossing matters more here than elsewhere.