2 companies just combined forces to create a massive chain of medical clinics that are changing the way Americans get healthcare

• FastMed and NextCare, two of the biggest urgent care companies in the US, said on Thursday that they're meraging.
• Urgent-care centers have become an increasingly popular way to get healthcare in the US. Big players - from health plans to hospital systems to private-equity investors - all want in on urgent care, which grew by 25% between 2014 and 2017.
• The growth is coming at a time when the way Americans access healthcare is changing.

Two of the biggest urgent care chains in the US - FastMed and NextCare - are combining forces.

Together, they'll have 251 urgent care clinics in 10 states, according to a statement. That would make the company one of the largest urgent-care chains in the US, rivaling industry leader MedExpress, which is owned by UnitedHealth Group.

Urgent care is catching on as Americans increasingly seek convenient ways to get healthcare. According to the Urgent Care Association, the industry's trade group, there were 8,154 urgent care centers in the US in 2017, up 25% from 2014. Urgent care visits have climbed rapidly, too.

Urgent-care centers don't require appointments, and can treat everything from a sore throat to a deep cut or minor fracture. The centers are usually staffed by doctors trained in emergency medicine and provide far more types of care than a retail clinic inside a pharmacy.

"They're definitely popping up everywhere," Dr. Lisa Bielamowicz, the president of Gist Healthcare, which consults with health systems, told Business Insider. "There's a huge amount of competition for the convenient-care space."

Terms of the transaction, in which FastMed is acquiring NextCare, weren't disclosed, though the companies said they expect the deal to be completed within 60 days. Private equity firms Abry Partners and BlueMountain Capital Management are FastMed's lead investors.

Read more: The doctor who founded CityMD and sold it for $600 million explains how a new kind of medical clinic is changing how Americans get healthcare

There have been other big-ticket deals for urgent care clinics in the past few years.

• In April 2017, private-equity firm Warburg Pincus took a majority stake in CityMD in a deal that reportedly valued the urgent-care company at $600 million.
• Optum, a unit of insurance behemoth UnitedHealth Group, bought MedExpress in 2015 for a reported $1.5 billion. MedExpress is the largest urgent-care operator in the US, with at least 250 locations.
• Private-equity firm American Development Partners in July 2017 said it would invest $1 billion in the second-largest operator, American Family Care, to help open more clinics.

• Read more:
• Amazon is dipping its toes into a $300 billion healthcare-technology market, and it has analysts wondering if the retail giant has a shot at disrupting it
• Why the doctor who cofounded CityMD opened an urgent-care clinic in Queens even though he knew it'd lose millions
• Top healthcare bankers from Morgan Stanley and Bank of America see a slowdown ahead after a record year for deals and IPOs
• The CEO of a $3.7 billion senior-care company went to a country facing a 'demographic time bomb,' and what he saw could be a lesson for the US