I found a reference about literacy in Massachusetts [0] and literacy for all states [1], but nothing suggesting literacy rates are worse than over 200 years ago. I would presume literacy rates for over 200 years ago would be worse due to lack of public education, gender inequality, and jobs/trades not requiring reading and writing skills.

I am suspicious of the literacy rates in [0] and [1]. It seems that someone who immigrates from a foreign country would be considered illiterate if they did not speak English, but had high proficiency in reading and writing in their native language. Not knowing one specific language is very different from being generally uneducated.

[0] https://mblc.state.ma.us/programs-and-support/adult-literacy...

[1] https://worldpopulationreview.com/state-rankings/us-literacy...