Born during the Great Depression, the fried onion burger was created in El Reno, Oklahoma out of a necessity for saving money when times were tough. Onions were cheap and meat was expensive, so why not add more onions and less meat, the locals thought. Little did they know this burger would go on to become a national treasure and delight the bellies of fellow Americans almost a century later. Take a look at El Reno - the epicenter of the fried onion burger.

The town of El Reno is just a short 25 minute drive from the heart of Oklahoma City and is now considered the "fried onion burger capital of the world."

El Reno was known as a popular stopping point along Route 66 when travelers were making their way across the Mother Road. The fried onion burger became a popular item to feed hungry visitors at an affordable price of just five-cents per meat patty.

The fried onion burger was once an under-appreciated burger that might not look pretty on the outside, but it's bursting onion flavor on the inside is unparalleled.

A fried onion burger is made by taking a big glob of onions and smashing it into a patty of beef on the grill. The caramelized onions infuse the patty with amazing flavor.

Every year the town of El Reno holds an El Reno Burger Day - a community event held in honor of the burger and to cook the largest fried onion burger on record.

The event takes place the 1st Saturday of May in Downtown El Reno. The 2017 date is May 6th.

The world's largest fried onion burger weighs over 750 lbs and is the most massive burger you'll ever see.

The burger is cooked on a 12-ft convection oven and a 10-ft circular grill. The burger consists of 250 lbs. of meat, 150 lbs. of onions and 350 lbs. of buns. The burger is then topped with pickles and mustard and cut up into pieces and handed out to visitors at the annual festival.

There are a few staple restaurants left in town that have been serving this delectable onion burger for decades.

One of the oldest establishments famous for the fried onion burger is Sid's Diner located at 300 South Choctaw Ave., El Reno, OK. Sid's has been featured on many television shows and serves incredible cooked-to-order onion burgers.

Another small town cafe is Robert's Grill - a 14 stool counter restaurant that's been serving patrons since 1926.

Robert's Grill is located at 300 South Bickford, El Reno, OK.

Johnnie's Grill has been in business since the 1940s and also serves the yummy fried onion burger with caramelized onions that are smashingly delicious.

Johnnie's Grill is located at 301 S Rock Island Ave., El Reno, OK.

Where is your favorite place in El Reno to get a fried onion burger?

Check out these 12 other fabulous restaurants in Oklahoma that serve mouthwatering burgers.