A local law says that residents of Saginaw Township in Michigan cannot publicly display political signs in support of a presidential candidate until 30 days before the US election, even on their own front lawns.But you wouldn’t know it while driving through this neat midwestern township that borders a town of the same name – simply, Saginaw – in the most closely contested county, also called Saginaw, of a battleground state that Donald Trump won in 2016 when he took the White House and then lost in 2020 when Joe Biden wrested it from his control.With more than six weeks until what many Americans regard as the most consequential US presidential election in decades, some Saginaw Township residents have defied the ban to declare their loyalties to their neighbors. Trump campaign signs outnumber those for Kamala Harris, but scattered among them are posters proclaiming that the former US president is a convicted felon who belongs in prison and not the Oval Office.One Saginaw Township resident interpreted the newfound unwillingness of local officials to enforce their own ban on political signs as a desire to avoid confrontation in these politically charged times.For Saginaw Township’s population, there is the added weight that not all votes are equal in the US thanks to the vagaries of the electoral college system and that theirs count for more than most. The county is crucial to who wins Michigan and the state looks likely to be pivotal in deciding the next occupant of the White House.In 2016, Trump beat Hillary Clinton in Saginaw county by just 1.1% of the ballot as he took Michigan by less than 11,000 votes. Four years later, Biden won back the county for the Democrats by only 303 votes as he once again returned the state into the Democratic column.View image in fullscreenThis year, the Harris campaign sees Michigan as a key part of its clearest path to victory alongside two other Rust belt states, Pennsylvania and Wisconsin. Saginaw county will be a litmus test of whether the Democratic nominee can pull that off and keep Trump from returning for a second term that many observers fear will risk authoritarianism in the USA.So Saginaw is an ideal place from which to observe this epic US presidential election, the third in a row with Trump on the ballot – and not just because the vote has been so close in the past. The state of this county mirrors many of the issues faced by other places that will decide this contest.Saginaw has a once-booming industrial base in long decline but which is still important. Widespread poverty exists alongside prosperous suburbs in a city with one of the highest crime rates in the country. There are changing racial demographics and, for many, a sense of drift with no clear plan for the future.In the US’s Democratic-dominated big urban centers – such as New York, Los Angeles and Seattle – it is not uncommon to hear Americans wonder how it is that this year’s election is even close given Trump’s political and criminal record. Many seem to be still grappling with the same questions that surfaced eight years ago when he stunned the nation by defeating Hillary Clinton. At times, it feels as if they regard places like Saginaw county as a distant, foreign landscape.Seen from Saginaw, however, the election can look very different.View image in fullscreenThe Guardian asked people who live in the county to tell us where we should go, who we should talk to and what we should look at in order to understand the area and its place in the election.Among those who replied was Geordie Wilson, a former teacher, who wrote: “Saginaw is possibly the most economically and racially divided area in the country. It is the epicenter of our national divide.”Several people mentioned their fears about the future of American democracy if Trump returns to the White House, including Jamie Forbes, who is recently married and works for the local public transport system. Forbes also spoke about the economy, a common theme nationally and locally. He said he wants to see “wealthy people and corporations paying their fair share in taxes”.“Saginaw issues: Continuing attempts for our economy to recover from automakers pulling jobs, attraction and diversification of new industry, crime, small business success,” he wrote.Valerie Silvernaile, a medical procedure scheduler, said it was important to protect workers’ rights in the industries that remain.“Unions are important here. We need a candidate who isn’t a union buster,” she said.One middle-aged man said he has never voted but will this year, for Trump: “Food prices, safety and jobs. Trump has addressed all of this for me between listening to him and his website.”Michael Colucci, a chemical engineer who has lived in Saginaw Township for 40 years, wrote that “you can visit all of America in a 20-mile stretch along M-46”, the Michigan highway running east to west through the county.View image in fullscreen“Most Americans live in communities where most people think like them. Saginaw is small enough that everyone has the occasion to interact with everyone else,” he said.Colucci, who lives in an electoral precinct where Trump and Hillary Clinton each won 49.5% of the vote in 2016, took the Guardian on a drive to show what he meant. It began in the city of Saginaw, which Colucci calls a “mini Detroit” for its abandoned factories and housing.In 1968, Saginaw was one of 10 communities across the US awarded the title of “All-America City” by the National Civic League. Those were the boom times.Since then, the population of the city has dropped by more than half to fewer than 45,000 people, as jobs disappeared and residents decamped. That also drove a change in Saginaw’s demographics. Twenty-five years ago, Saginaw city was about evenly divided between white and Black residents in addition to a Latino minority. The white population has dropped sharply, to less than 35%.Colucci pointed out mansions built by the lumber barons whose sawmills drove the city’s 19th-century development when demand for timber from Michigan’s pine forests surged as the US colonised lands to the west. But more often, there were just grass-covered patches of ground where auto factories and shopping malls once stood.Some of the first cars built in America were assembled in Saginaw. Over decades, factories drew in workers from across the country to manufacture gear boxes and steering assemblies fitted into vehicles in Detroit. Saginaw city and its environs were home to a dozen General Motors plants.skip past newsletter promotionafter newsletter promotionBy the 1980s, the industry was in rapid retreat from Saginaw. The last GM plant, today called Saginaw Metal Casting Operations, employed 7,000 people in 1970. Now it provides work to fewer than 350.The factories stood abandoned for years, symbols of a lost prosperity, until the Biden administration provided funds to tear them down. When the jobs went, shops and hotels closed. In the heart of downtown, department stores have given way to public services including an employment office, a college and a healthcare centre for lower-income families.View image in fullscreenA brand-new school opened on the riverbank this month. But it, too, is a testament to decline after attendance at the city’s two main high schools, once sharp sporting rivals, fell so low that they were closed and combined.Simon & Garfunkel’s iconic 1960s song America was written in the city and includes a line about taking “four days to hitch-hike from Saginaw”. Fifteen years ago, an artists collective, Paint Saginaw, daubed lyrics from the song on dozens of abandoned factories, bridges and empty buildings, including the line: “All gone to look for America,” as a lament to people moving out. But the population had not so much gone to look for America as shuffled a few miles down the road.As Colucci drives west, he crosses from the city, passes the sprawling golf course of Saginaw Country Club, and heads into the suburbs of Saginaw Township.In 1980, the city was nearly four times as large as the township. Now, they are about the same size after many residents of one bled into the other. But the township has nearly twice the median income and is 89% white.Crossing from one to the other, the quality of housing changes fast. So do the voting patterns.Saginaw city overwhelmingly voted against Trump in both the presidential elections he contested. Clinton won 76% of the ballot in 2016 and Biden pulled in similar support four years later.Saginaw Township was a different story. Trump beat Clinton there by three points in 2016. Four years later, he lost by a similar margin to Biden.In other words, it wasn’t the poorest part of Saginaw that once delivered for Trump but one of the most prosperous. Colucci has an explanation.“Trump promises them that he’s going to stop the world from changing,” he said.Then he scoffs: “He promised to stop coal disappearing and it literally disappeared while he was president.”The outcome of this election is likely to hang on turnout. Trump’s vote in Michigan went up in 2020 but he was beaten because many of those Democrats who stayed home four years earlier came out to remove him from the White House.View image in fullscreenColucci volunteered for Clinton’s campaign but lamented that her organisers placed too much confidence in data, didn’t listen to local advice and failed miserably to mobilise Democratic voters on election day. It is an often bitterly expressed complaint heard repeatedly over the years across Rust belt states that Clinton should have won.Biden’s campaign evidently did better and there are clear signs that Harris has learned the lessons. But the challenge remains.Nearly 75% of registered voters in Saginaw Township cast a ballot in the 2020 presidential election. Fewer than 50% of Saginaw city turned out.In other Trump strongholds such as Frankenmuth, a small city in the south-east of the county known as Little Bavaria, turnout was 82%. Frankenmuth, which celebrates its German heritage in its architecture and its own Oktoberfest this weekend, twice voted overwhelmingly for Trump and his anti-immigrant agenda.Still, nothing is a given.Among those who contacted the Guardian was Mark Paredes, a former US diplomat and lifelong conservative who said he would never vote for Trump and is therefore supporting Harris.“If you had told me 10 years ago that I would be doing this, I would have been quite amused,” he wrote. More