Final answer:
Corn syrup and corn starch became popular in the United States in the 19th century, with corn starch usage starting early in the century and corn syrup following later. High Fructose Corn Syrup (HFCS) gained prominence in the 20th century, particularly after 1970 when it started to replace cane sugar.
Step-by-step explanation:
The popularity of corn syrup and corn starch in the United States can be traced back to the 19th century. Corn starch began to be used widely in the early 1800s as a starch for laundry and other industrial purposes. Its food use also began around this time. The development of corn syrup, however, occurred later. The production of corn syrup became common after the invention of the roller milling process and the discovery of the enzyme-based process for making it.
High Fructose Corn Syrup (HFCS), a form of corn syrup, became particularly prominent in the 20th century. According to an infographic (Figure 3-20b), since 1970, HFCS has been cheaply produced and has largely replaced cane sugar, leading to a significant increase in total sugar consumption in the US. This indicates that the 20th century marked a substantial rise in the popularity of corn-based sweeteners.