Google’s position as the search advertising leader in the US is on solid footing, according to our latest US digital ad spending estimates. This year, Google will net more than 73% of US search ad spending, down less than 1 percentage point since 2018.

By the end of our forecast period in 2021, Google will have lost more than 2 percentage points more in share. The winner there will be Amazon, which has been the second-largest search ad seller in the US since 2018, when it surpassed Microsoft.

Overall, search ad spending is growing robustly, driven by spending on the market leaders. This year, search outlays will rise by almost 18%, and doubled-digit increases will continue through 2021.

These growth rates, in line with digital advertising as a whole, mean search will hold on to just less than a 43% share of the total digital market through 2023, per our forecast.

Search placements continue to perform well for advertisers. Amazon’s ad business, for example, has attracted massive increases in ad spending because advertisers can reach audiences via interest-based signals—product queries—and in a context where they’re ready to buy.

Still, even a tried-and-true format involves plenty of new wrinkles for marketers to monitor. As more search queries come from voice devices—and more results are returned the same way—the possibilities for paid voice search remain blurry. And visual search has the potential to take off on smaller platforms like Pinterest as well as the search giants.