Visitors turn out despite high temps in D.C. (AP) WASHINGTON - One word could describe visitors to the Capitol Fourth Concert Wednesday night: sweaty. Despite high temperatures and the threat of thunderstorms, thousands of visitors from across the continent took part in Independence Day celebrations in the nation's capital. The Carter family from El Paso, Texas, set up lawn chairs facing the Washington Monument at 8:30 a.m. By 1 p.m., they still were stretched out in the shade of a tall tree, armed with umbrellas and water for the anticipated grueling sun that would steal their shade in the midafternoon. At 4 p.m. a youth group from a church in New Brunswick, Canada, sang and played guitar in Franklin Square with a sign on their guitar case reading, "Need a dollar, take a dollar." They planned to go to the fireworks on the National Mall as a break from a week of service work visiting Washington's elderly and homeless. The National Park Service urged attendees to use public transportation to avoid traffic during the holiday. Unlike in years past, the Smithsonian Metro Station - the station closest to the Mall - remained open. At 12:30 p.m. there already was a steady flow of visitors coming at Smithsonian, chugging water from plastic bottles. Three uniformed officers stood watching the crowd. "Have your fare cards ready with the arrow pointing up," one man yelled over the din. A new communications service allowed the U.S. Park Police to send texts directly to visitors to Washington this Fourth of July and to warn them to take precautions to deal with the intense heat. "Drink plenty of fluids, use sunscreen, and seek shade to ensure a safe and healthy July 4 celebration," read a text sent through the newly-implemented Nixle service Wednesday. Park Police spokesman Sgt. Paul Brooks said the service was not new to police, but that they are the first federal agency to use Nixle. Without electricity, many party like it's 1776 Brooks named the temperature as one of the main concerns this year. The heat index on the National Mall was 100 degrees Wednesday afternoon. Washington boasted a variety of events during the day including the annual parade and a playing out of the signing of the Declaration of Independence at the Jefferson Memorial. A Capitol Fourth Concert was scheduled to start on the Capitol west lawn at 8 p.m., ending at 9:30 p.m., the same time as the 20-minute fireworks show on the Mall. Thunderstorms threatened to disrupt the evening's Capitol Fourth Concert and fireworks, but National Park Service spokesman William Line said it would take more than a drizzle to shut down the festivities.