In Big Bend National Park my husband, father, daughter and I stood on the banks of the yellow-green waters of the Rio Grande.

On our side – the US side – we planted our feet on a beach of cracked mud. On the other side, a 1,000ft cliff wall rose from the river to run left and right, as far as the eye can see. It was the sort of picturesque photo-op that National Parks are built for.

I pointed across the river and told my father: “That’s Mexico,” to which he replied: “Well if that’s Mexico, why does Donald Trump need to build a wall?”

The adults laughed at the joke and my three-year old asked if she could go potty – all of us unaware that we were in an area that is sometimes referred to as the border zone.

I didn’t imagine that within the next six hours, I would be locked in a cell by US Border Patrol. My offense? I’m Canadian and I didn’t have my permanent resident card with me.

It began with a stop at the Border Patrol station approximately 80 miles north of the entrance to Big Bend, and just over 100 miles north of the Mexico–US border.

“You all American?” a Border Patrol agent asked.

“No, I’m Canadian!” I said cheerfully – not thinking that my answer would prompt furrowed brows.

“What’s your status?”

Another easy question, I thought. “Permanent resident.”

They asked for my permanent resident card – which I didn’t have with me. But I did offer my driver’s license and my university ID, neither of which were of interest to the agents. When my septuagenarian father identified himself as a Canadian citizen visiting from Montreal, he was asked for his passport. “I didn’t think I needed to carry it because we weren’t crossing any borders”, he said. “Why do I need it?”

I thought it was a good question.

My husband asked: “Do you need to see my ID?” The agent’s replied: “What for?”

It might be worth mentioning here that my husband is Italian-American, from New Jersey. I am a first-generation Canadian of Trinidadian-descent. My husband and I aren’t the same color.

In the mid-1990s, I moved to the US for graduate school before moving to Austin, Texas, in 2007. I was born and raised in Montreal – less than 50 miles from the Canada-US border and only a seven-hour drive to New York City. Growing up, my family made that drive countless times to visit relatives who lived in Brooklyn and Long Island.

In those days, we presented our passports and politely answered all of the questions asked of us. It was a routine that always occurred at the border – not in a border zone – which I didn’t know existed before I traveled within 100 miles of the frontier between Mexico and the US. Aside from the picture-worthy mesas, glimpses of roadrunners and a string of Rock Shops, the border zone is the thing you pass through when you leave a day of family-fun in Big Bend.

It took almost an hour, but the agents were able to confirm that my father had flown into the US, from Montreal, on a Canadian passport. Yet they could not verify that my permanent resident card had not expired. Three agents repeatedly explained that I am required to carry my permanent resident card with me at all times – a fact that I only became aware of in the border-zone. There, after an hour of circular-questioning, a bullet-proof-vested agent said: “Ma’am, we need you to step out of the car.”

Inside the makeshift station I was told: “You are in direct violation of the law. This is a question of border security.” And I was asked to remove my shoelaces, shoes, scarf and “anything that you can hurt yourself with”.

“Please, don’t do this,” I begged. “Can I please wait with my family in the car?” One agent took a break from spitting tobacco into the bucket at his feet to watch his colleague back me into a 5 x 10ft cell – a cell complete with a seat-less toilet and some un-artistic graffiti which included the likes of swastikas and gems such as: “Militarize our borders to maintain our white-power structure.”

After four hours of detainment, and after they agreed to allow a friend of mine in Austin email them a photo of my permanent resident card, and after they told me that they’d done me a courtesy, a border patrol agent smiled, said: “You’re free to go” and pointed to where my shoes sat.

I can’t remember slipping my feet into my shoes, or walking back to the car, but I do remember grabbing my daughter and sobbing in our sensible sedan.

“Why are you crying mummy?”

“Because I’m happy to see you.”

“Why?”

“Because I didn’t know if I would get to have dinner with you tonight.”

“Why?”

“Because I had to prove that I could be here, with you.”

While Donald Trump shares his ideas on the value of a really big wall, the United States Customs and Border Protection spends upwards of $38bn annually to safeguard America’s borders and “serve the American public with vigilance, integrity and professionalism”.

I consider myself part of the American public. I have a social security card. I pay taxes. And a trip to a National Park the weekend before Thanksgiving seemed like a good way to celebrate my husband’s 40th birthday.

I didn’t realize that not bringing my permanent resident card would result in my loss of freedom.

In this age of increasing fear, the US Customs and Border Protection has a growing responsibility – not only to protect the American public, but also to help mitigate fear. This mandate will not be accomplished through an abuse of power.