The number of Americans signing up for coverage through HealthCare.gov dropped by a half-million for 2017, as efforts by President Donald Trump and congressional Republicans to demolish the Affordable Care Act propelled the first enrollment decline in its history. The lower total, with 9.2 million consumers choosing health plans in ACA marketplaces through the enrollment deadline Tuesday, marks a striking turnabout from the trend as former President Barack Obama’s administration neared its end – when sign-ups for coverage under the law were running steadily ahead of a year ago.