Bloomberg, the billionaire mayor who transformed New York

Billionaire Michael Bloomberg will go down as one of New York's most transformative mayors but he has divided an electorate set to elect his polar opposite.

The 71-year-old tycoon, who founded the successful news and financial data company Bloomberg, steps down on January 1 after a record 12 years.

Thanks to a vast wealth that beholds him to no-one, he won respect - if not love - for driving forward an agenda and avoiding some of the shabby compromises of office.

According to a recent Wall Street Journal/NBC poll, only 18 per cent of registered voters believe he has performed poorly.

"What the Bloomberg reign most profoundly demonstrated is the power of an extremely wealthy man who is beholden to no special interests," according to Forbes magazine. "Bloomberg effectively created his own special interests and used the government to turn a city into a data-driven, health-conscious image ... of himself."

Bloomberg loves reeling off statistics as testament to his success: the lowest murder rate in 50 years; at 52 million, a record number of tourists; life expectancy up by 2.5 years in the last 12 years. Violent crime, the great scourge of New York until the 1990s, continues to drop.

Bloomberg's aggressive public health policies, such as banning smoking in bars and restaurants, have contributed to a 50 per cent decline in teen smoking.