Mining
Trona, hydrated sodium bicarbonate carbonate (Na3HCO3CO3·2H2O), is mined in several areas of the United States and provides nearly all the domestic sodium carbonate. Large natural deposits found in 1938, such as the one near Green River, Wyoming, have made mining more economical than industrial production in North America.

It is also mined out of certain alkaline lakes such as Lake Magadi in Kenya by using a basic dredging process and it is also self-regenerating so will never run out in its natural source.

Barilla and kelp
Several "halophyte" (salt tolerant) plant species and seaweed species can be processed to yield an impure form of sodium carbonate, and these sources predominated in Europe and elsewhere until the early 19th Century. The land plants (typically glassworts or saltworts) or the seaweed (typically Fucus species) were harvested, dried, and burned. The ashes were then "lixiviated" (washed with water) to form an alkali solution. This solution was boiled dry to create the final product, which was termed "soda ash;" this very old name refers to the archetypal plant source for soda ash, which was the small annual shrub Salsola soda ("barilla plant").

The sodium carbonate concentration in soda ash varied very widely, from 2-3% for the seaweed-derived form ("kelp"), to 30% for the best barilla produced from saltwort plants in Spain. Plant and seaweed sources for soda ash, and also for the related alkali "potash," became increasingly inadequate by the end of the 18th Century, and the search for commercially-viable routes to synthesizing soda ash from salt and other chemicals intensified.