A new conference will form in 2018, and several local high schools will be part of it.

Athletic directors from Districts 4, 5 and 6 came to an agreement Tuesday at Century High School — Century, Pocatello and Preston will merge with six schools from District 4 to create a new 4A conference.

Tuesday’s decision is the latest development in a surge of classification changes that will alter the entire state next year. The athletic directors at Tuesday’s meeting believe that a new District 4-5 conference will benefit every school involved.

“Those are good schools, Century, Preston, Poctello,” Twin Falls athletic director Ted Reynolds told the Times-News on Wednesday. “I think they’ll be good for our conference.”

Twin Falls, Canyon Ridge, Jerome, Burley, Minico and Wood River have made up the Great Basin Conference (4A District 4) since 2009, when Canyon Ridge opened. Century, Pocatello and Preston have competed with various District 6 schools over the same amount of time. The current 4A District 5-6 conference includes Blackfoot, Idaho Falls and Skyline.

Thunder Ridge High School, in Idaho Falls, is set to open in the fall of 2018. The 5A school will take students from Bonneville and Hillcrest, forcing those two to drop from 5A to 4A. Shelley also plans to move up from 3A to 4A, leaving District 6 with six 4A schools.

Instead of forming a nine-team conference with District 6, District 5 opted to join its neighbors to the west (the new District 4-5 conference will still be called the Great Basin Conference, Jerome AD Jeremy Munroe said).

A handful of factors played into the decision, from financial considerations to competitive balance. District 5 wanted to avoid a three-team conference, the Idaho State Journal reported, and District 4 saw intriguing benefits of a nine-team conference.

One of those benefits is the addition of automatic state tournament berths.

“With a six-team conference, we’re probably going to get 1 1/2, maybe two, berths, depending on the year,” Reynolds said. “If we go to a nine-team conference, we’re going to get three. It makes for a more competitive conference, and gets us better representation in the state tournament.”

There’s a chance the conference will expand to 10 teams.

Mountain Home petitioned to move down from 4A to 3A in 2018 based on its competitive history, and the Idaho High School Activities Association approved the petition. The school also hoped to leave District 3 and join the Sawtooth Central Idaho Conference (3A District 4), the Idaho Statesman reported. The SCIC is currently occupied by Buhl, Filer, Gooding and Kimberly.

In a meeting Wednesday, Mountain Home’s petition was denied by the IDHSAA, multiple sources told the Times-News.

A stay in 4A, however, does not mean the Tigers will remain in District 3. They could join the Great Basin Conference if both sides like the idea.

Mountain Home, which is located about 90 miles away from Twin Falls, would increase travel time and costs for GBC teams. But Preston’s distance from Twin Falls is twice as far as Mountain Home’s, and local athletic directors agreed to add the Indians to the GBC.

Every school would prefer to take short trips for its road games. But Tuesday’s decision did not drastically change the travel reality for GBC schools.

“All of us play a lot of those schools anyhow,” Reynolds said of Century, Pocatello and Preston. “To have them be in our conference, it makes those non-league games mean something now. A lot more games count when you’re in a bigger conference.”

Correction: This story has been updated to clarify that the IDHSAA initially approved Mountain Home's petition to move down to 3A.

UPDATE (10/5): Mountain Home athletic director John Clark confirmed that the IDHSAA denied the school's petition to move down from 4A to 3A, he told the Times-News on Thursday. Clark didn't have any information as to why the petition, which was initially accepted, was rejected.

Mountain Home will also petition to join 4A District 4-5 next season, Clark said. If the Tigers are accepted, the Great Basin Conference will include 10 schools beginning in the fall of 2018.

Twin Falls AD Ted Reynolds, among others in the GBC, likes the idea of adding Mountain Home to the conference.

"We have no problem with them if they want to come over here," Reynolds told the Times-News on Wednesday. "It would be kinda neat to have them come over, but that would be up to them."