It's midday and the US Border Patrol are leading a procession of exhausted people up from the riverbank. They've just crossed the border between Eagle Pass, Texas, and Mexico. They're soaking wet and caked in mud and some have lost their shoes. The heat is fierce and there's no shade. Where they've come from, how they got here, and what happens to them now is the subject of huge political controversy.

We spend so much money in guarding other countries' borders, but we can't even come down and actually acknowledge the fact that we have a significant crisis here in the Texas border.

Should the US just turn them away and say, no, you can't come into the US because we can't handle any more people. I don't accept that. I think the US can handle more people.

The Rio Grande River forms about half of America's 2,000 miles long border with Mexico. Another group leaves the comparative safety of the shore to make the difficult crossing. On the day we filmed, a Border Patrol officer told us that 1,700 people cross the river like this at Eagle Pass. You can see how the current pulls at them. By the time they reach the other side, many have been swept a long way downstream and must fight their way back against the flow of water and in the relentless heat to find an exit point. Many don't make it.

This is where we come. They bring in the patients. We start doing CPR right here.

Manuel Mello is the Fire Chief of Eagle Pass, Texas, a border community of 30,000 people that's the location of one of the busiest migrant crossing points.

So right here, we're pretty close to the city of Eagle Pass, downtown district.

Chief Mello, whose team are also the town's paramedics, says many migrants are sadly unprepared for how dangerous the river is.

The white water is because there's a lot of gravel and sand where they actually can cross and walk through there. But if they slip and they hit a dip like this one right here, they will be swept away by the water.

It's a grim task, you.

Call it. We're doing about sometimes 2-3 times a week, we come down to the river, not necessarily for drowning, but for injuries in the summer for heat exhaustion. But it's about 2-3 times a week that we come down here. Sometimes it's unpredictable. Sometimes we'll do even up to five calls once a day.

Between the chief and the river patrol boat is the source of many migrant injuries, the layer upon layer of razor wire. Having survived the river's currents, the exhausted migrants, including children, must find a way through this wire. This girl, no more than six or seven, does make it through. Others, like this woman, get stuck, unable to go forward or back. The wire was put there by the state of Texas, run by Republican governor Greg Abbott, and it's against the wishes of US Border Patrol, run by the Democratic Party President Joe Biden. This border has become highly politicized. This stretch of riverbank at Eagle Pass is owned by Hugo and McGilly, Urbina. They farm peacans or would do. Their crop is a tenth of what it should be. Their trees have been choked with the dust from the constant Border Patrol vehicles. What do you think of the wire that's been put on your land and the fences?

Well, actually, the US Border Patrol did not put this. The state of Texas put this up. And the state of Texas actually did a taking of our property, which is unconstitutional. It's against the law and it's against our wishes.

Traveling from South America, from Venezuela, and they crossed the Daderean gap, they walked through several states through Mexico. This is not going to stop them. They're coming across.

And do you feel like you're in the middle of a political football here?

We've seen quite a few candidates are running for President. We've been down here. We've seen a lot of people from Congress on both sides, Republican and Democrat. You don't have to. It doesn't matter whether you're a Republican or a Democrat. There's right and wrong and what's happening here is wrong. It doesn't matter what spectrum or side you're in. Most people here in Yagur Pass happen to be Democrats, but they'll tell you they're not happy.

Once the migrants are across the river and through the wire, they're taken into custody by Border Patrol agents. They're divided into men, women, and families. Shoe laces and belts are removed and most of their baggage is dumped. They're then photographed along with any documents. Many here told us they were from Venezuela. What strikes you about these crossings is not simply the scale, hundreds of people wading through the river at any one time. It's also the efficiency of the system. Within 18 to 24 hours, everyone here is likely to be on their way on busses to towns and cities across America. It's that distribution, much of it on busses paid for by the government of Texas that's causing huge political ruckions in big American cities. Many that had previously welcomed incomeers now say they're at capacity and can't cope. The chair of the local Democratic Party in Eagle Pass, Juanita Martinez, is very supportive of Joe Biden. But on this issue, she says there needs to be more federal help.

I think they should pass some legislation to make it easier, to make the process better, where you don't wind up having immigrants having to risk their lives on the river, putting these coyotes out of business because let's face it, they're making money. Because these people that come, the ones that we have rescued, the ones we've helped, you'd be surprised how much money they took from them. But that's not the most precarious thing that they go through because they come from Venezuela, because, evidently, there's a problem in Venezuela that maybe the federal government could go and help.

But Republicans like Hugo Erbina are looking for an entirely different response.

President Biden was to say anybody who crosses illegally to United States will be sent back to the prior country. I guarantee you, Mexico will make a stop and said, We don't want these people here because you're going to... And they won't be coming in because the cartels asking for them to pay them a significant amount of money, and they're not going to come all the way over here just to be sent back.

And that would deter, you think?

Significantly. I know President Trump did that at one point.

Having been photographed and processed, today's arrivals line up for the busses that will take them to a local shelter for a few hours rest, some food and fresh clothes. Adult children go to separate facilities from their younger siblings. There is anxiety, but there is also hope. More than a quarter of a million people arrive in the US like this every month. Even with its vast resources, America is struggling to cope.