Extreme heat wave hits parts of the US and Canada The strong heat wave hitting the United States has put millions of people on alert, put pressure on the power grid and affected the country's Independence Day celebrations. In Washington and other cities, authorities canceled or postponed dozens of parades, concerts and performances. One of the main events affected was the Great American State Fair, set up on the National Mall in Washington. The attraction is part of the celebrations for the 250th anniversary of US independence promoted by President Donald Trump. ? The fair, which brings together representatives from the 50 American states, was temporarily closed on Friday afternoon (3), when thermometers reached 38°C. Hours later, organizers of the official Independence Day parade announced the cancellation of the event due to safety concerns. The event was scheduled for 10:30 am this Saturday (4), but the thermal sensation could reach 46°C, according to the National Meteorological Service. Record temperatures reached the eastern US driven by a "heat dome", a phenomenon in which a high pressure system traps a mass of hot air over a region and increases humidity. A man wipes his face during a heat wave at the Brower Skate Park in New York, United States. Reuters Cancellations in several states Cancellations spread across several parts of the East Coast of the USA during the 4th of July holiday, when Americans celebrate the country's independence with barbecues, parades and fireworks shows. In Philadelphia, authorities canceled the traditional Salute to Independence Parade, one of the main events of local celebrations. The decision was taken after the city recorded 39.4°C on Thursday, equaling the temperature record set in 1901. Other cities followed suit. Haddon Township, New Jersey, has canceled its annual Fourth of July parade. Watertown, in upstate New York, suspended the Independence Day concert and fireworks display. In Boston, the opening to the public of the traditional festival with fireworks on the banks of the river was postponed by four hours, from noon to 4 pm (local time). An employee uses an umbrella to protect themselves from the sun during a period of extreme heat in the Washington region, at the entrance to the Great American State Fair. Reuters Electric grid under pressure The intense heat also put pressure on the electrical system. PJM, the country's largest electricity grid operator, advised consumers enrolled in emergency energy saving programs to reduce consumption. According to the company, the measure was necessary to face failures in generators, the overload of transmission lines and the strong increase in demand for air conditioning. In New York, utility Con Edison reported that around 17,000 customers were without power late Friday afternoon. Faced with increased consumption, the company asked residents of New York City and Westchester County to save electricity. People seek shade in the Washington region, at the Great American State Fair, held as part of the celebrations for the 250th anniversary of US independence. Reuters More than 185 million under warning According to the National Weather Service, about 185 million people — more than half the US population — were under a heat warning this Friday. In some regions, the thermal sensation reached 46°C, while several cities broke temperature records. Meteorologists warned that the heat wave could be fatal and recommended that anyone spending the holiday outdoors should increase their hydration, seek shady places and pay attention to signs of exhaustion caused by high temperatures. Children cool off in water jets after the Great American State Fair temporarily closed due to the heat on the National Mall in Washington. Reuters Taylor Swift's wedding attracts fans despite the heat In New York, the heat was so intense that the soles of shoes ended up sticking to the Manhattan asphalt because the glue softened with the high temperatures. Even under an extreme heat warning, fans remained on the sidewalks to watch the arrival of celebrities at Madison Square Garden, where the wedding party between singer Taylor Swift and American football player Travis Kelce was expected. An employee guided the arrival of the SUVs, holding a bottle of water in one hand and a towel in the other to wipe off sweat. * With information from Reuters news agency