The 1961-D Lincoln cent is one of the worst struck cents from 1932 to date. As of 2010, it is one of a handful of Lincoln cents from the 1930's to 2010 that does not exist in MS67 grades or higher.
In the early 1960's, the Denver Mint stepped up production of circulation strike Lincoln cents and even outpaced the Philadelphia Mint. This resulted in very poor quality Lincoln cents being struck for circulation from 1960 to 1963.
The 1961-D along with the two consecutive years include the 1962-D and 1963-D Lincoln cents, which also do not exist in PCGS MS67 Red grade. These three Denver coins are three of four different Lincoln cents that do not exist in PCGS MS67 grade or higher. The other only date of business strike Lincoln cents from 1930's to date which is non existent in MS67 grade, is the 1973-S.
Therefore, the 1961-D, 1962-D, 1963-D and 1973-S Lincoln cents are the worst quality circulation strike cents produced from the 1930's to date.