NEW YORK: Total digital ad spending in the US is projected to surpass TV advertising for the first time in 2017, according to the latest quarterly forecast from eMarketer.

The research firm said next year will "mark a major milestone" when TV ad spending in the US reaches $72.01bn, or 35.8% of total adspend, while digital rises to $77.37bn, or 38.4% of total expenditure.

TV adspend is still expected to grow by 2.5% this year, but eMarketer lowered its growth projection of 4.5% that it forecast in Q3 2015. Over the longer term, it expected TV adspend to slip to about 2% growth a year.

And with other media channels continuing to expand, TV advertising in the US is expected to account for less than a third of total adspend by 2020, the report said.

"We still expect positive growth for TV adspend, driven by political advertising and the summer Olympics," said Martin Utreras, senior forecasting analyst at eMarketer.

"However, we see more ad dollars flowing to digital as a way of optimising spending in what may be a challenging economic year," he added.

By contrast, digital ad spending is expected to record strong growth of 15.4% this year, taking the total dedicated to digital to $68.82bn.

Mobile is fuelling spending growth in digital, eMarketer reported as it forecast mobile adspend in the US will grow 38% this year to equal $43.6bn. That means mobile will represent 63.4% of total digital adspend in the US this year.

"As consumers continue to increase engagement with mobile devices for daily activities and content consumption, marketers will further integrate all marketing activities—including advertising—to the mobile category," said Utreras.

Data sourced from eMarketer; additional content by Warc staff