On Navajo Nation, the Native American territory of nearly 71,000 square kilometres spanning Arizona, Utah and New Mexico, the post can take 10 days to arrive.
In Arizona, there are more than 46,600 square km of reservation but only 27 post offices, some of which are open for only three hours a day.
It is the equivalent of having 13 mailboxes in the entire state of New Jersey.
This month, a federal appeals court rejected a lawsuit from the Navajo Nation, which requested the deadline for mail-in ballots be extended because of the slow mail service and distances between polling stations.
The lawsuit, filed by a handful of Navajo voters in Arizona, said that their ballots should still be counted if they were received after 7pm on election day but postmarked before November 3.
Arizona state law requires ballots to reach the recorder’s office by 7pm on election day.
Indigenous communities say the law breaches the Voting Rights Act of 1965 by giving Navajo voters less opportunity to vote than other Arizonans.
Three judges from the 9th US Circuit Court of Appeals said voters had not shown how the deadline would harm their ability to vote.
The said the lawsuit was “replete with general allegations concerning the various hardships the Navajo Nation members who live on the reservation generally face with respect to mail voting”.
“Although we do not discourage challenges to voting laws that may be discriminatory or otherwise invalid, whenever they may arise, we are mindful that the Supreme Court ‘has repeatedly emphasised that lower federal courts should ordinarily not alter the election rules on the eve of an election',” judges Margaret McKeown, Jacqueline Nguyen and Robert Whaley said.
The court also raised questions about the difficulty of using information on ballots to try to distinguish between Navajos living on tribal lands and other voters.
Mr Trump won Arizona by just 91,000 votes in 2016. There are 67,000 voters in the state’s Navajo Nation and their vote could play a pivotal role in the election’s outcome.
Recent polling by Real Clear Politics shows President Donald Trump’s Democratic rival Joe Biden up by 2.7 percentage points in Arizona, making the state a battleground.
If the Democrats clinch the state, they would upend a long-standing history of Republican wins.
“People are really worried their vote will not be counted in this election,” says O J Semans, co-director of Four Directions, a Native American voting rights organisation that has been working on the issue for almost two decades.
“The hardship that they have to go through to even participate in the election is one thing.
"But then for them to actually cast a ballot and not have it counted in such a hotly contested race in which a lot of native issues are online, they're very worried about their voice not being heard because of the disadvantage they have in being able to participate.”
Mr Semans’s group has tested postal times inside the reservation and in the mianly white communities outside.
Certified first-class mail posted to the Maricopa County recorder’s office from Scottsdale, Arizona, arrived within 18 hours.
But the mail sent to the same address from areas in the Navajo Nation took up to six days.
Although voters in Arizona can drop off their ballots at polling locations, there is one polling station for every 800 square km on the reservation, compared to one for every 34 square km in Scottsdale.
“You have to allow five to seven days for your voting ballot to get to you,” Mr Semans said.
“Most people check their mail around once a week, because they live so far away, it can be as far as 40 miles [64km] away.
"They have to drive down primitive roads that are only roads because they drove down them once before.
"If your ballot hasn’t arrived yet, you then have to figure out if you want to spend more money on gas checking again.
"If you’re lucky and your ballot is there, then you have other problems. Most elders on the reservation speak [only] their traditional language.”
The issue has been compounded by the coronavirus pandemic. Plans to set up satellite polling stations were scrapped because of safety fears.
“Indigenous communities have been robbed of their land and in many ways are robbed of their votes too,” says Saad Amer, co-founder and director of Plus1Vote, a voter organisation.
“Obstacles like geographic isolation, lack of traditional addresses and housing insecurity disproportionately prevent indigenous communities from casting their ballots.”
Mr Amer said voter-ID requirements, internet availability and voter purges further disenfranchised Native Americans.
With 4.7 million indigenous people eligible, “we have to do all we can to ensure they can vote”.
“It is essential that these communities are represented and have a voice in what happens to their land and our planet.”
Manuel Fulton, 52, who lives in Porcupine, Arizona, with his wife and four children, said: “There’s a lot of frustration among people who live on the Nation.
“People can live miles off the highway and some of our roads are dirt, and when it rains they can become impassable.
“Now, with the pandemic, casting our vote has become even harder. We have to spend money on gas, Even trying to find that money to spend is hard.
“Every time it comes to election time, I always feel like there might not even be any point in voting because we don’t even know if it will get there.”
Mr Semans said: “In some cases, you could mail that ballot 10 days before the election and that ballot still may not make it to the clerk reporter in the county.
"So your votes aren't going to get counted. There's no doubt in my mind the process for Native Americans to vote has purposely been made difficult.”
