What was the 1978 Deutsche Mark worth in US dollars?

If your question relates to the numismatic value of a 1978 Deutsche Mark coin, it is worth less than a dollar in circulated condition, and US$1 to US$2 in uncirculated or proof condition. This is the case regardless of which mintmark (D,F,G or J) you are referring to.

If your question relates to the Dollar-Deutsche Mark exchange rate in 1978, US$1.00 = DM2.00 (FYI, it was US$1.00 = DM2.32 in 1977 and US$1.00 = DM1.83 in 1979).