Counties included in the declaration range from the Panhandle across the northern tier of the state from north-western to north-eastern Oklahoma.
Earlier, officials said one of three wildfires in the Texas Panhandle is now 100% contained.
Multiple wildfires are still burning across the Texas Panhandle following Monday's elevated fire conditions across the Southern Plains.
The fire that originated in Gray County is now burning in Wheeler County as of 11:18 p.m.
The largest fire, dubbed the Perrytown Fire, has consumed over 300,000 and is only 50% contained, according to the Texas A&M Forest Service. Background: Wildfires destroy hundreds of thousands of acres in the Texas Panhandle Tuesday, March 7, 2017.
The fire is only about 5 percent contained but the winds have died down since Monday.
Poultry industry officials urge precautions against bird flu
H7 HPAI, a highly pathogenic strain of avian flu, was found in the sample from the Lincoln County flock. Other flocks in the quarantined area are being tested for the virus, it added.
The Texas A&M Forest Service and the National Weather Service Storm Prediction Center forecast that winds, which help stoke the wildfires, will subside on Wednesday.
Hutchinson Fire Chief Doug Hanen said crews would continue to work on hot spots in the area throughout the day on Thursday.
The largest was in Clark County, where about 545 square miles has burned.
"Mostly we're just very thankful", Richele Calvert said.
"These fires are so important that we take our time and have containment lines because of the strong winds behind it".
Evacuations for Higgins and Glazier residents has been lifted.
IEA warns of oil supply crunch unless drillers build new projects
That newfound investment vigor and projections for stronger shale production have kept a lid on the recovery. Oil fell in NY as clashes between armed factions in Libya curbed crude output, while US drilling increased.
According to the Kansas Division of Emergency Management, almost 632,000 acres have burned during the recent fires, including 502,000 acres in Comanche and Clark counties. Officials say they haven't been able to contain the fires at all as of Wednesday morning.
In Kansas, wildfires have burned about 625 square miles of land, said Katie Horner, the spokeswoman for the state's Department of Emergency Management. Crews went to homes and structures in the area looking for victims.
Kansas National Guard Black Hawk helicopters have been assisting with the firefight.
CNN reports that a 63-year-old Oklahoma woman died of a heart attack while fighting wildfires in alongside her husband in Harper County, Oklahoma. The fires destroyed one "inhabited structure", some barns and "a big hog production complex". He said temperatures should top in the 70s, with afternoon humidity low. That fire started in Oklahoma before moving into the Kansas ranching community.
Comanche County Emergency Manager John Lehman says the ground is "extremely dry", so it's possible the fire could re-ignite.
Mauricio Pochettino hails Tottenham's belief after holding out for win over Everton
Asked after the match how it had come about, Kane explained - and worrying added we might not have seen the back of it. His opening effort was both superbly struck and, from an Everton perspective, entirely preventable.