For Mike Vickers, not much has changed here since 1823, the year a group of frontier lawmen formed the Texas Rangers to protect settlers and their land.

“We’re still dealing with the bad guys from Mexico,” Vickers, 69, told The Post, referring to smugglers who traffic in drugs and migrants. “This is a war.”

Dressed in a cowboy hat, tan cargo pants and weathered boots, Vickers, a veterinarian, runs Las Palmas Animal Hospital, but he’s also chairman of the Texas Border Volunteers, a 300-strong militia helping thinly spread Customs and Border Patrol agents cover more than a million acres of private land throughout the state’s border counties.

Thirty Volunteers armed to the teeth patrol the hundreds of thousands of acres of ranchland near this city of nearly 5,000. And they are expecting an influx of smugglers this weekend.

“We always have big traffic at Easter,” he said. “It’s a big smuggling week for us.”

The land, cut by mesquite and cactus, lies nearly 90 miles from the Mexican border but only 4.5 miles from a US Border Patrol checkpoint.

Traffickers want to avoid this interior checkpoint — located on the only highway in this part of the state — so vehicles crammed with drugs or migrants from Central America and even China drop off the migrants and smugglers south of the checkpoint.

Smugglers and their human cargo jump fences onto private ranches to traverse the vast expanses on foot.

The mesquite canopy is ideal cover, allowing them to hide from drones and National Guard helicopters that patrol the area.

“You never know what’s under that next tree,” said Vickers, whose 1,000-acre spread is one of the area’s smaller ranches.

The mission is dangerous for the Volunteers, and the journey is deadly for the migrants.

There is an emergency call station in the middle of one ranch where migrants can summon the Border Patrol for help, Vickers said. The call station has messages in Spanish and Mandarin, as well as a tank with jugs of water.

“We always investigate a buzzard or a bad smell,” Vickers said, adding that since it began patrolling in 1988, his group has found more than 100 bodies of migrants who died crossing the terrain.

The modern-day posse, made up mostly of retired military, dress in camo fatigues and begin their patrols at dusk using night-vision goggles that are more sophisticated than those used by Border Patrol, Vickers said.

They conceal their weapons “out of respect for law enforcement,” Vickers said. Vickers carries a rifle in his SUV, and two .380-caliber handguns in the pockets of his shirt and pants.

He also keeps a .45 Long Colt Taurus called “The Judge” under the driver’s seat of his Suburban. His wife, he said, carries a smaller model known as “The Public Defender.”

“The tough women stay,” he told The Post.

“The weak and timid ones leave. I’m married to a tough one, and we’ve been together for 23 years.”

Despite their weapons, Vickers claims the Volunteers have never fired a shot and try not to confront migrants. When they come upon a group, they radio nearby Border Patrol officers, he said.

The militia works in tandem with the Border Patrol and local law enforcement. If they find a group of smugglers or migrants, they wait until the feds or a deputy from the Brooks County Sheriff’s Office arrives on the scene.

Sometimes they see the same smugglers over and over again, said Elias Pompa, a deputy, who patrols the county and relies on the intelligence-gathering of the Volunteers to help him patrol more than 1,000 square miles.

“They just keep doing the same thing over and over again,” he told The Post. He said they arrest the smugglers and hand them over to the Border Patrol.

After smugglers serve out their time in prison, they are deported, although many keep returning to do the same thing, he said.

Many ranchers left after traffickers torched their homes or painted death threats on their property. One rancher saw two homes burned down, Vickers said.

To protect his own ranch, Vickers, who supports President Trump’s proposed border wall, has installed his own barrier — a 220-volt electrified fence.

Migrants have still tried to dig under it.

“I put it up years ago to protect my daughters when they got to high school and started to come home late after cheerleading or sports practice,” he said.

“Sometimes there would be strange people waiting by the gate asking my daughters for a ride,” Vickers said.

“I wasn’t about to take any chances.”

Even if Trump’s wall gets built, Vickers said he will continue to do his part to defend private land.

Nearly 200 miles away in Brownsville, Texas, Rusty Monsees is also prepared to protect his own land, although the federal government installed a border barrier nearby a decade ago.

The 71-year-old ex-cop owns 21 acres in the Rio Grande Valley, where a 60-mile fence built during the Obama administration bisects part of his property. He carries a rifle in his truck and says he has his own group of volunteer landowners who patrol ranches and alert Border Patrol agents to suspicious activity.

“It’s not an influx we have; it’s an invasion,” he told The Post.

Monsees claims the current rust-colored fence, conceived in the final Bush administration, is ineffective.

At 18 feet, it’s not high enough to keep anyone out, and the rough surface allows for easy climbing, he said. There are also 35 large gaps.

The Department of Homeland Security said it is plugging the holes with automatic gates.

“You have to build a fence that actually stops people from coming in,” he said.

One day last week, Monsees said, he and a neighbor watched Border Patrol agents round up dozens of migrants. “We saw them fill 12 busloads in a three-hour period,” he said.

Vickers also came across a large group on a patrol Wednesday night.

“We had quite the show,” he said, recalling that his unit came across more than 30 migrants — many Asian — and reported them to Border Patrol, who detained 17.

“The rest got away,” he said.

The Volunteers received a warning from one of the smugglers, who monitor their radio communications.

“He said in Spanish, ‘I’m going to hunt you down and chop you into a thousand pieces with my machete,’” Vickers said with a hearty laugh. “We’re staying and fighting. We’re never giving up.”