MEXICO CITY—A broad ban on single-use containers, forks, straws, and other ubiquitous items takes effect in Mexico’s capital, one of the world’s largest cities, after more than a year of preparation. On Friday, Mexico City’s environmental secretary said via Twitter that “from today on Mexico City [is] without single-use plastics.” The message urged people to think of always carrying reusable containers in a similar fashion to never leaving home without their cellphones. Mexico City lawmakers passed the ban on plastic bags, utensils, and other disposable plastic items in 2019. The city of 9 million people has spent the past year adjusting or in some cases ignoring the impending law change. The ban on plastic bags took effect last year. Light, allegedly biodegradable bags have become more common at the city’s street food stalls. Plastic straws are offered less often. Fresh tortillas are handed over wrapped in paper or cloths that …