Social media marketing is the leading SEO service priority among U.S. businesses in 2018, according to new research from Clutch and Ignite Visibility. Over 90% of businesses that invest in SEO also invest in social media.

The survey of 303 marketing decision-makers at U.S. businesses reveals that most tend to shape their SEO strategy based on the SEO services they prioritize and the challenges they face.

Two factors impact the direction of a business' SEO strategy: The shifting customer journey and whether the business focuses on paid search or organic SEO services.

Organic SEO services include:

• On-site optimization – web design, site infrastructure, blogging

• Off-site optimization – content marketing, social media marketing

Over 40% of businesses that invest in SEO focus on organic services, compared to 19% that focus on paid search.

Businesses that focus on organic SEO are more likely to use in-house staff for general marketing, such as content marketing and social media. Over three-fourths (76%) of businesses that focus on organic services use in-house staff.

On the other hand, businesses that focus on paid search are more likely to hire an SEO company. More than two-thirds (68%) of businesses that focus on paid search hire an SEO company, compared to just 37% that rely on in-house staff.

Paid search complements organic SEO by providing feedback on keyword research, audience targeting, and effective ad copy, said Eythor Westman, head of paid media at Ignite Visibility.

How businesses adapt to shifts in the customer buying journey is another factor that shapes SEO strategy. The rise of mobile search drives changes to the customer buying journey.

SEO experts agree that customers use their mobile devices to learn about a company through social media and site content before converting to make a purchase.

"Now, somebody Googles a keyword. Then they click on a top ranking term like, 'SEO company.' They read our blog and click around social media," said John Lincoln, CEO of Ignite Visibility. "Then, they convert three weeks later after they feel comfortable with you."

In response, businesses prioritize SEO services that facilitate the customer journey. Along with social media (20%), businesses rate creating content to earn links (15%), and mobile search optimization (14%) as their top SEO priorities.