(CNN) — For those on a quest to visit all 50 United States, each one is like a jagged piece of a very large jigsaw puzzle.
Fitting in all 50 states is an impressive achievement. In fact, anyone who knocks 35 off the list is eligible for membership in the exclusive All Fifty Club, an organization that recognizes individuals who make it to every state with a plaque or certificate to commemorate their accomplishment.
To "visit" a state, a person has to step outside the airport and breathe the air, according to the organization's website. Airport layovers mean nothing.
Those who are truly passionate about making it to all 50 states often have their own criteria for crossing them off the list, from a hard-core requirement of staying in a state for more than a month to simply hopping out of the car to snap a picture at the border.
CNN asked avid 50-staters to run down their requirements. Here's how it's done:
Go beyond the border
Back in 1976, Don Carswell of New Jersey, now 53, and his friend Tom White made a bet to see who would be the first one to set foot in all 50 states. At stake was a six-pack of beer.
In order to count a state as "visited," the two men agreed that they had to spend at least one full hour in a state during the day, be outdoors at least part of the time, set foot on the actual ground, and go beyond the state's border. Airport property also didn't count.
The bet lasted 15 years, until Carswell received a postcard from White declaring he had reached his 50th state. Carswell was still two states shy of completing his goal, making sure he followed the criteria they set when they first made the bet.
It took seven more years for Carswell to visit Oregon, the one state he needed. "Being one state shy annoyed me. I needed to take matters into my own hands," he said.
Sent to San Francisco on business in 1998, he extended his stay to rent a car and drive north to Oregon.
"I was sure to send Tom a card," Carswell recalled. It simply said, '50!' "
Let the kids choose
Together the Holmes family of Pennsylvania has traveled to 40 states. Their oldest child, Cate, is barely a teenager.
Wendy Holmes says that she and her husband, Chris, have been taking their 13-year-old daughter Cate and 7-year-old son Tom on trips since they were infants. Once Cate and Tom were old enough, Holmes and her husband started letting them take turns deciding where the family would go each year. Because the family often drives to their destinations, they try to stop in as many states as they can in one trip.
"We're not competitive," Holmes said, but they are strategic. "We do have plans on which states to visit over the next few years so that we do hit 50 before our daughter leaves for college."
Holmes keeps track of the states they've seen in an Excel spreadsheet, using the list to plan what stops they'll make on future trips.
"We drive so much on our vacations and camp a lot. We've actually gotten out and seen the states."
The family typically stays in each state they visit for three days, but apart from how long they stay, there's really only one other agreed-upon criterion.
"My husband has (visited) 46 states. He's not allowed to get to 50 unless we're all together."
Go back to fill in the blanks
Justin Clark Pollard had a deadline to meet.
He and his wife, Dana, had been taking long road trips during their summers off from teaching since 2009. It wasn't until their second big road trip in 2012 that they saw how close they were to visiting all 50 states, and they decided to go for it. But Pollard wanted to push this goal even further. The deadline: His 30th birthday.
"I used (turning) 30 as a reason to do this, to keep traveling places I might not go otherwise," he said.
On an old road atlas he keeps in the glove compartment of a baby blue Nissan, Pollard kept track of all the states he and his wife visited.
At the bare minimum, he considers getting a snapshot at a state's border beneath the welcome sign enough to circle it on his map. But on average he and his wife try to stay in each state at least two days.
They even took seasonal jobs at Glacier Bay National Park in Alaska for seven weeks so they would have the opportunity to really witness its wildlife.
When they got back home to Georgia after their Alaska trip, Pollard's deadline was fast approaching. With only three weeks until he turned 30, the couple packed up and raced to hit the two states they had yet to see: Michigan and Wisconsin.
Despite their short stay in each state, Pollard was not disappointed.
"No matter how much time I stay in a state, I'm never going to see the whole thing," he said.
These road trips are "highlight trips." Now that he and his wife have seen all 50 states, they're able to stay in one place a little longer.
"On the road trips we saw what all the states were known for, and now we can go back and explore them in depth."
Connect with people
Long-time friends Kristin Sweetman and Katie Stern, both 29, have put their lives on hold to embark on a seven-month journey across the country, volunteering in each state they visit.
"We were both at points where we needed direction in our lives. We were both in ruts and needed a change to do something else," said Sweetman, who quit her job before leaving on this trip.
Since the two women started on their journey from their homes in Minnesota on April 28, they have already picked up nine states. They have been staying in each state for anywhere from three to five days, devoting one full day to volunteering and staying at campsites or with other volunteers they work with.
In West Virginia, the women worked in a community garden with Conscious Harvest Cooperative, a group of West Virginia University students and Morgantown residents who grow food for local pantries. In the Adirondacks in upstate New York, they found a local farmer and helped him grow tomatoes. Next, they're volunteering in Boston with Hope Lodge, baking snacks for the families of cancer patients.
They're journaling and blogging about their experiences in each state, and they use a calendar to keep themselves organized and on track. But they're really in no rush to finish their journey across the country. They want to live in the moment and see where it takes them, Sweetman says.
"We want to connect with the different people we meet on this trip," Sweetman said. "There are so many people who have opened their homes and their hearts to us, and that's how we get a true idea of what a place is really like."