• by Laurie Sullivan  @lauriesullivan, July 12, 2017

Local media spend is estimated to reach $174 billion by 2021.

Mobile, social and video will drive the 3.8% compound annual growth rate, according to the BIA/Kelsey forecast released Wednesday.

The midyear revenue update to BIA/Kelsey's U.S. Local Advertising Forecast 2017 suggests a slight decline to $147.9 billion in 2017, on an overall weaker-than-expected economy and softer-than-expected advertising revenue.

Weaker numbers in 2017 won't last. 

However, BIA/Kelsey forecasts higher-than-expected numbers through 2021, growing at a CAGR of 11.9% for online advertising. During the same time frame, traditional advertising revenue will see a slight decrease between 2016 and 2021, with a CAGR of -0.6%.

Direct mail will take the largest share at 25% or $37.1 billion in 2017. Local TV follows with 14% share or $21 billion.

Online interactive, newspapers and mobile all take an 11% share each. They help round out the top five with revenue of $18.6 billion, $16 billion and $16 billion, respectively.

This year, mobile replaces local radio as the fifth top revenue-generating media for local advertising. Local radio will earn $15.6 billion.