The differences that once distinguished Hong Kong from the rest of China have become more blurred every year since the handover. Even the mention of a 'border' between the Special Administrative Region and Guangdong has become politically incorrect.
Borders, after all, define international frontiers, not artificial divisions within the same nation. 'Boundary' is the preferred term, and marks a return to the past. It was the wording used up until the 1920s, and its use was even formalised. Until 1997, the perpetually busy Boundary Street in Kowloon marked what was - in purely legal terms - probably the world's strangest international frontier.
As well as passing through the middle of one of the world's most densely crowded areas, Boundary Street marked the dividing line between British Kowloon, ceded 'in perpetuity' to Great Britain in 1860, and the New Territories, leased from China for 99 years in 1898.
Following the second Anglo-Chinese war (1856-1860), variously known as the Arrow war or the second opium war, the Kowloon peninsula and Stonecutters Island were ceded to the British Crown in the Treaty of Tientsin, which ended hostilities. An arbitrary boundary line was drawn on a map across the northern section of the Kowloon peninsula - so straight that one suspects a ruler was run across a map - and a bamboo dividing fence with a gate was erected.
This rudimentary international border divided 'British Kowloon' (south of the arbitrary boundary and legally part of the crown colony) from what was at that time a series of isolated village settlements whose inhabitants scratched a hand-to-mouth existence from their fields.
Kowloon rapidly developed and prospered, as had Hong Kong Island before it, and expanded beyond the 'boundary' laid down in 1860. That part of the Chinese mainland immediately beyond British Kowloon became known as 'New Kowloon', and comprised modern Sham Shui Po, Lai Chi Kok and the environs of Kowloon City. An administrative no-man's land by the 1880s, free movement of people - and goods - was the norm.