It was a Tuesday.
September 20 1951 was a Thursday.
September 26th 1951 was a Wednesday.
September 3 1951 was a Monday.
15 September 1951 was a Saturday.
September 19, 1951 was a Wednesday.
September 20, 1951 was a Thursday.
September 7 1951 was a Friday.
If you mean what day of the week in 1951, then it would be a Sunday.
September 5, 1951 fell on a Wednesday.
September 28. 1951 fell on a Friday.
September 13, 1951 fell on a Thursday.
September 28th, 1951 fell on a Friday.