Company Names, addresses, dates¹:
  Root Pop Bottling Co, 208-210 Mass Ave NE, Washington DC (1928-1929) ^1,2
  Root Pop Bottling Co, 413 2nd Street, NW Washington DC (1934-1946) ^1,3
  Root Rock Bottling Works, 413 2nd Street, NW Washington DC (1935-1946) ^1,4
  Root Rock Ginger Ale Co, 413 2nd Street, NW Washington DC (1944-1949)

Notes:
The earliest reference I can find to Root Rock or Root Pop was that Root Pop was listed in the 1929 Washington DC city directory, at 208-210 Mass Avenue, NE. In previous years, that address had been the home of the California Bottling Company, run by George Mezitis.¹

Louis G. Harris (ca.1893-1942) came into the employ of the Root Rock Beverage Company in 1928 according to his obituary, so it seems that the company started at least a year before it was listed in the city directories. Harris was the assistant General Manager when he passed away in 1942.²

The city directories don't list Root Pop or Root Rock between 1930 and 1943, but I see newspaper references about the company/companies in most of the years between 1934-43, so I suspect it was in operation during that time.

A large newspaper ad for Root Rock in 1937 listed George Mandes as the General Manager, Louis Harris as the Sales Manager, and Frank Harper as the Route Manager. At that time, it was 15 cents for two 32-ounce bottles. The ad has a picture of a 32-ounce bottle, and the label on said bottle resembles the labels at the bottom of this web page.⁵


Root Pop Bottles:

book # 598 This is a clear 9.5" crown top bottle embossed: front: Root Pop / BOTTLING CO, INC/ WASHINGTON, D.C. heel: CONTENTS 9 FL OZ. PAT APPLIED FOR

book # 599 This is a clear 9.2" crown top bottle embossed: front: ROOT POP / BOTTLING CO / INC / CONTENTS 9 FL. OZS. back: ROOT POP / BOTTLING CO / INC / DESIGN PATENT 81642 base: WASHINGTON DC / [G] / 149-1 This bottle has the same design pattern as one of the root-rock bottles below. I have one like this that says "PATENT APPLIED FOR" instead of "DESIGN PATENT 81642", so I suspect that this design was for a "Root Pop" bottle before it was for a "Root Rock" bottle.

	book # 600 This is a clear 9.2" crown top bottle. One of the circles seems like it has an upside-down heart etched in it - I'm not sure if this was by design or if it's a defect. Definitely doesn't look like a bubble-burst. Bottle is embossed: front: ROOT ROCK / BEVERAGES / CONTENTS 9 FL OZS back: ROOT ROCK / BEVERAGES / DESIGN PATENT 81642 base: 7314 2B40 WASHINGTON DC
	book # 602 This is a 10" clear stippled crown top bottle with faded red & white Applied Color Label (ACL): front: REFRESHING-HEALTHFUL / ROOT ROCK / FAMOUS FOR IT'S TASTE / Sparkling / Bracing / Beverage / ROOT ROCK / BEVERAGES back: Contains / FILTERED / CARBONATED WATER / CANE SUGAR / FLAVOR, CITRIC ACID / CERTIFIED COLOR / SEE CROWN / FOR OTHER INGREDIENTS. / CONTENTS ONE PINT / BOTTLED BY / ROOT ROCK BEVERAGES / WASHINGTON, D.C. embossed on the base: ROOT ROCK BEVERAGES / WASHINGTON, D.C.
	book # 602 This is just like the above bottle, except it's green (and it's smooth instead of stippled). It is a 10" green crown top bottle with a red/white ACL: front: REFRESHING-HEALTHFUL / ROOT ROCK / FAMOUS FOR IT'S TASTE / Sparkling / Bracing / Beverage / ROOT ROCK / BEVERAGES back: Contains / FILTERED / CARBONATED WATER / CANE SUGAR / FLAVOR, CITRIC ACID / CERTIFIED COLOR / SEE CROWN / FOR OTHER INGREDIENTS. / CONTENTS ONE PINT / BOTTLED BY / ROOT ROCK BEVERAGES / WASHINGTON, D.C. embossed on the base: ROOT ROCK BEVERAGES / WASHINGTON, D.C.
	book # 603 This is similar to the above bottle, except that it is not stipled, and the markings are all white with no red. It is a 10" aqua crown top bottle with a white ACL: front: REFRESHING-HEALTHFUL / ROOT ROCK / FAMOUS FOR IT'S TASTE / Sparkling / Bracing / Beverage / ROOT ROCK / BEVERAGES back: Contains / FILTERED / CARBONATED WATER / CANE SUGAR / FLAVOR, CITRIC ACID / CERTIFIED COLOR / SEE CROWN / FOR OTHER INGREDIENTS. / CONTENTS ONE PINT / BOTTLED BY / ROOT ROCK BEVERAGES / WASHINGTON, D.C.
	book # 603 This is similar to the above bottle, except the color of the glass is green. It is a 10" green crown top bottle with a white ACL: front: REFRESHING-HEALTHFUL / ROOT ROCK / FAMOUS FOR IT'S TASTE / Sparkling / Bracing / Beverage / ROOT ROCK / BEVERAGES back: Contains / FILTERED / CARBONATED WATER / CANE SUGAR / FLAVOR, CITRIC ACID / CERTIFIED COLOR / SEE CROWN / FOR OTHER INGREDIENTS. / CONTENTS ONE PINT / BOTTLED BY / ROOT ROCK BEVERAGES / WASHINGTON, D.C.
	book # 604 It is a 7.75" clear crown top bottle with stipling, rope design, and 4 clear cirlces. It's marked with a green & white ACL: front: ROOT-ROCK / FULL / OF HEALTH / STEINIE BEVERAGES back: MADE WITH / PURE CANE SUGAR / AND / FILTERED / CARBONATED WATER / FLAVORS DERIVED FROM / NATURAL FRUITS / CERTIFIED COLOR ADDED / CONTENTS 12 FL. OZS. / ROOT ROCK BEVERAGES / WASHINGTON, D.C. embossed on the base: ROOT-ROCK / BEVERAGES / WASHINGTON, D.C. I beleive that "STEINIE BEVERAGES" refers to the fact that this is a "steinie" style of bottle. The "steinie" style of bottle was created by Owens-Illinois glass company in 1936 and features a wide body with a bulge between the bottle & the neck6.
	book # (unlisted) This is similar to #602, but larger & it has some embossing. It's an 11.75" clear crown top bottle with stipling that says: ACL on front: REFRESHING-HEALTHFUL / ROOT ROCK / FAMOUS FOR IT'S TASTE / Sparkling / Bracing / Beverage / ROOT ROCK / BEVERAGES ACL on back: Contains / FILTERED / CARBONATED WATER / CANE SUGAR / FLAVOR, CITRIC ACID / CERTIFIED COLOR / SEE CROWN / FOR OTHER INGREDIENTS. / CONTENTS ONE QUART / BOTTLED BY / ROOT ROCK BEVERAGES / WASHINGTON, D.C. Embossed on front/back shoulder : ROOT ROCK Embossed on base : ROOT ROCK BEVERAGES / CONTENTS / ONE / FULL QUART / WASHINGTON, D.C.
	book # (unlisted) This is an 11.75" tall bottle with 2 labels that say: neck label: REFRESHING HEALTHFUL / ROOT ROCK / FAMOUS FOR IT'S TASTE large label: Sparkling / Bracing / Beverage / ROOT ROCK / PALE DRY / GINGER ALE / MIN. CONTENTS 32 FL. OZS. / Refreshing-Healtful / ROOT ROCK GINGER ALE CO. / WASHINGTON, D.C. Embossed on base : CONTENTS / 1 FULL QUART
	book # (unlisted) This is an 8.0" tall marchine-made green bottle embossed: front heel: ROOT ROCK BEVERAGES rear heel: CONTENTS 7 FLUID OUNCES base: WASHINGTON / [G] / 1388 / 2 / D.C. The 'G' in a square embossed on the base means it was made by the Glenshaw Glass company.

	This is a brown & white bottle cap that says: top: ROOT ROCK / RR TRADE MARK REG. / ROOT BEER / COLORED WITH CARAMEL / ROOT ROCK BEVERAGES / WASHINGTON, D.C. edge: AJAX
	This is a yellow & black bottle cap that says: top: ROOT ROCK / RR TRADE MARK REG. / ORANGE / ARTIFICIAL FLAVOR AND COLOR / ROOT ROCK BEVERAGES / WASHINGTON, D.C. edge: AJAX
	This is a black & white bottle cap that says: top: ROOT ROCK / MIN CONT 7 FL OZ / RR / TRADE MARK REG. / ROOT BEER / COLORED WITH CARAMEL / ROOT ROCK GINGER ALE / CO. / WASHINGTON, D.C. edge: AJAX
	This is a colorful label that says: Sparkling / Bracing / Beverage / ROOT ROCK / GRAPE SODA / ARTIFICIAL FLAVOR AND COLOR / MIN. CONTENTS 16 FL. OZS. / Refreshing-Healthful / ROOT ROCK GINGER ALE CO. / WASHINGTON, D.C.
	These labels say: top label: REFRESHING HEALTHFUL / ROOT ROCK / FAMOUS FOR ITS TASTE main label: Sparkling / Bracing / Beverage / ROOT ROCK / STRAWBERRY SODA / ARTIFICIAL FLAVOR AND COLOR / MIN. CONTENTS 16 FL. OZS. / Refreshing-Healthful / ROOT ROCK GINGER ALE CO. / WASHINGTON, D.C.
	These labels say: top label: REFRESHING HEALTHFUL / ROOT ROCK / FAMOUS FOR ITS TASTE main label: Sparkling / Bracing / Beverage / ROOT ROCK / GOLDEN / GINGER ALE / ARTIFICIAL FLAVOR AND COLOR / MIN. CONTENTS 16 FL. OZS. / Refreshing-Healthful / ROOT ROCK GINGER ALE CO. / WASHINGTON, D.C.
	These labels say: top label: REFRESHING HEALTHFUL / ROOT ROCK / FAMOUS FOR ITS TASTE main label: Sparkling / Bracing / Beverage / ROOT ROCK / ORANGE SODA / ARTIFICIAL FLAVOR AND COLOR / MIN. CONTENTS 16 FL. OZS. / Refreshing-Healthful / ROOT ROCK GINGER ALE CO. / WASHINGTON, D.C.
	These labels are larger than the previous ones, as they're for a 32-ounce bottle. They say: top label: REFRESHING HEALTHFUL / ROOT ROCK / FAMOUS FOR ITS TASTE main label: Sparkling / Bracing / Beverage / ROOT ROCK / STRAWBERRY / ARTIFICIAL FLAVOR AND COLOR / MIN. CONTENTS 32 FL. OZS. / Refreshing-Healthful / ROOT ROCK GINGER ALE CO. / WASHINGTON, D.C. Other flavors of ROOT POP from Washington DC that I've seen include: PALE DRY GINGER ALE, LEMON-LIME, and ROOT POP.