Half of America is under winter weather advisories as freezing temperatures grip the country

By Hollie Silverman, CNN

    (CNN) -- Nearly 170 million people are under winter weather advisories Monday, with icy roads, power outages, and dangerously low temperatures threatening to snarl traffic and paralyze cities from coast to coast.

In the nation's heartland, at least 11 people have died in weather-related vehicle accidents since cold temperatures took hold of the country. Nine died in three separate incidents in Texas Friday, one person was killed in Kentucky, and another died in a wreck in Oklahoma Sunday.

Over half a million customers were without power as of early Monday morning, with the majority of outages reported on the coasts in Oregon and Virginia.

The severe winter weather has sparked emergency declarations in at least seven states, including Alabama, Oregon, Oklahoma, Kansas, Kentucky, Mississippi and Texas -- which has borne the brunt of the cold weather.

Officials in Harris County, Texas warned residents during a press conference Sunday night to stay indoors.

"The window to prepare for this historic storm has closed as the time to hunker down is here," Harris County Judge Lina Hidalgo said, adding that the dual threat of ice on the ground and extreme cold weather is going to pose "serious challenges."

Historic lows in Texas

Houston police responded to more than 130 traffic accidents Sunday night, Police Chief Art Acevedo said in a tweet.

A ten-car pileup on I-45 south of downtown was just one of many incidents on icy roads.

"Please avoid traveling until this severe weather event subsides," Acevedo said.

Mayor Sylvester Turner, who declared a state of emergency earlier in the day, echoed the chief's orders

"Please stay off the roads tonight and through tomorrow. This is serious! The roads are dangerous!"

Icy roads in the state have already proved deadly. A pile-up north of Houston in Fort Worth Friday involving more than 130 cars killed six people and injured dozens more, with at least 65 people seeking treatment at local hospitals following the crash.

On top of the danger icy roads pose, the mayor also cautioned residents that the weather could cause rolling black outs.

Early Monday morning, nearly 135,000 customers were without power in the state, according to Poweroutage.com. The Electric Reliability Council of Texas (ERCOT) is asking consumers and businesses to reduce their electricity use as much as possible through Tuesday.

"We are experiencing record-breaking electric demand due to the extreme cold temperatures that have gripped Texas," said ERCOT President and CEO Bill Magness.

"At the same time, we are dealing with higher-than-normal generation outages due to frozen wind turbines and limited natural gas supplies available to generating units. We are asking Texans to take some simple, safe steps to lower their energy use during this time."

Houston and surrounding areas are under their first ever wind chill warning. Every county in Texas, Oklahoma, and Arkansas is currently under a winter storm warning.

Cold snap from coast to coast

Below freezing temperatures are forecast to affect more than 245 million people in the lower 48 states over the next seven days, with more than 50 million Americans expected to experience temperatures below zero.

The cold air is so widespread that you could travel nearly 2,000 miles from the Rio Grande on the Mexican border to the St. Lawrence River on the Canadian border entirely in winter storm warnings or watches.

There is the potential for more than 240 cold temperature records to be broken by Tuesday evening, and some records have already been shattered.

Oklahoma City has gone a record five days without climbing over 20 degrees -- they are not expected to top 20 degrees until Thursday, for a stretch of nine days.

"This cold snap is forecast to result in record low temperatures that are comparable to the historical cold snaps of Feb 1899 & 1905," according to the National Oceanic and Atmospheric Administration.

Along with the unusual, widespread cold comes snow events that could also break records.

Seattle has already reported more than 11 inches of snow over the weekend, the most since January 1972, almost 50 years ago.

Cities in the south, including Dallas and Oklahoma City, have the potential for their biggest snowfall in a decade, and between two snowstorms this week, have their snowiest weeks on record.