Broadway—New York City’s theatrical center—was briefly called the “Gland Canyon” (gland + Grand Canyon) in the late 1920s and early 1930s. “Gland Canyon” was printed in the Miami (FL) Daily News on October 13, 1929, taken from the book Hangover: A Novel of Broadway Manners (1929) by Max Lief (a former writer on the New York Daily News).
   
“From wisecracker to highjacker, from 15-and-5 taxi driver to $5 cover night club pirate, from beminked show girl to casting-couch producer—the ladder is long, but the dizzying denizens of the Gland Canyon known as Broadway somehow climb it.”
 
“Gland Canyon” appeared in Broadway columnist Walter Winchell‘s syndicated newspaper column in 1932.
   
“Big/Hardened/Main Artery” is another anatomical description of Broadway. “New York, the nation’s thyroid gland” was written by American journalist and novelist Christopher Morley (1890-1957) in the 1940s.   
           
   
Wikipedia: Broadway theatre
Broadway theatre, commonly known as Broadway, refers to the theatrical performances presented in the 41 professional theatres with 500 or more seats located in the Theater District and Lincoln Center along Broadway, in Midtown Manhattan, New York City. Along with London’s West End theatre, Broadway theatre is widely considered to represent the highest level of commercial theatre in the English-speaking world.
 
The Theater District is a popular tourist attraction in New York City.
 
Wikipedia: Grand Canyon
The Grand Canyon (Hopi: Ongtupqa; Yavapai: Wi:kaʼi:la, Navajo: Tsékooh Hatsoh, Spanish: Gran Cañón) is a steep-sided canyon carved by the Colorado River in Arizona, United States. The Grand Canyon is 277 miles (446 km) long, up to 18 miles (29 km) wide and attains a depth of over a mile (6,093 feet or 1,857 meters).
 
The canyon and adjacent rim are contained within Grand Canyon National Park, the Kaibab National Forest, Grand Canyon-Parashant National Monument, the Hualapai Indian Reservation, the Havasupai Indian Reservation and the Navajo Nation. President Theodore Roosevelt was a major proponent of preservation of the Grand Canyon area, and visited it on numerous occasions to hunt and enjoy the scenery.
 
eBay
Hangover:
A Novel of Broadway Manners
By Max Lief
New York, NY: Horace Liveright
1929
Front flap:
FROM wisecracker to highjacker, from 15-and-5 taxi driver to $5 cover night club pirate, from beminked show girl to casting-couch producer—the ladder is long, but the dizzying denizens of the Gland Canyon known as Broadway somehow climb it.
 
13 October 1929, Miami (FL) Daily News, “The Book Nook” by Barend Beek, society sec., pg. 5, col. 5:
From wisecracker to hi-jacker, from 15-and-5 taxi driver to $5 cover night club pirate, from beminked show girl to casting-couch producer—the ladder is long, but the dizzying denizens of the Gland Canyon known as Broadway somehow climb it.
 
22 April 1932, Evansville (IN) Courier, “On Broadway” by Walter Winchell (During illness of Mr. Winchell this column is being conducted by Paul Yawitz), pg. 8, col. 7:
I have seen more Park Avenuers on the Gland Canyon than on the other side of the Great Social Divide (Sixth Avenue—ed.).
 
2 May 1932, New Orleans (LA) Item, “On Broadway” by Walter Winchell (During illness of Mr. Winchell this column is being conducted by Paul Yawitz), pg. 8, col. 3:
Geo. Lauder became bored with the Howard Hughes yotting party and returned to the Gland Canyon.
 
Google Books
Jackets Required
By Steven Heller and Seymour Chwast
San Francisco, CA: Chronicle Books
1995
Pg. 30:
HANGOVER
Boni & liveright,
1929
Designer unknown
A conventionally stylized rendition of the “dizzy denizens of the Gland Canyon known as Broadway.”