Washington, Dec 22 : The US, currently the world's hardest-hit country by the pandemic, has set yet another grim milestone as its overall caseload has surpassed the 18 million mark, while the deaths surged to more than 319,354, according to the Johns Hopkins University. In its latest update on Tuesday morning, the University's Center for Systems Science and Engineering (CSSE) revealed that the country's total caseload and death toll stood at 18,029,528 and 319,354, respectively. The US' latest infection tally makes up for more than 23 per cent of the global caseload. California reported the most cases, standing at 1,907,483, followed by Texas with 1,602,988 cases and Florida with 1,212,581 cases. Illinois registered 905,069 cases and New York identified 857,049 cases. Other states with over 500,000 cases include Ohio, Georgia, Pennsylvania, Tennessee and Michigan, the CSSE data showed. US Covid-19 cases hit 17 million on December 17, and added 1 million in just four days. The past week witnessed record numbers of cases, deaths as well as hospitalisations across the states. On December 18, the US reported 249,709 new cases, the highest number of daily cases so far since the pandemic began, according to data complied by Johns Hopkins University. On December 16, the daily deaths surged to 3,668, the greatest loss of lives in a single day since the start of the pandemic, showed the university's chart. /IANS