Broadband penetration in the US has increased by more than 300 per cent since 2002, according to new research.

Analyst firm Scarborough Research found that 12 per cent of US adults had a broadband connection in their household in 2002, compared to 49 per cent who subscribe currently.

This increase of more than 300 per cent brings broadband to a "mainstream level", the analyst firm claimed.

DSL connections grew more than cable modems, but both have expanded significantly. Cable modem penetration has increased 188 per cent since 2002, while DSL connections increased 575 per cent.

San Francisco emerged as the top local US market for broadband penetration, according to the report, where 62 per cent of adults live in a household with a broadband internet connection.

Other top broadband markets include Boston and San Diego, both of which have 61 per cent of adults with a broadband connection in their household.

"There is obviously an increasing need for more high-speed internet connectivity as it enables fast and efficient delivery of rich media content," said Gary Meo, senior vice president of digital media services at Scarborough Research.

"Consumers are clearly demanding more speed in order to upload, download, post and interact with content in a web 2.0 environment."