It gets a bit more difficult to accumulate the most popular names before 1880, to get these, the census has to be gleaned and filtered for birth year. I'm using this site as a reference for prior to 1880:

The 1870s saw these boys names most frequently given:

William,5693
John,5649
Charles,3476
James,3163
George,3021
Henry,1746
Joseph,1689
Frank,1677
Thomas,1632
Edward,1538
Robert,1268
Frederic,1168
Harry,892
Samuel,870
Albert,824
Walter,779
Lewis,757
Arthur,589
David,573
Benjamin,433

From this document.

and the following girls names:

[ad#htext]

Mary,6634
Ann,2998
Elizabet,2645
Emily,1870
Ada,1772
Ellen,1734
Margaret,1650
Catherin,1614
Sarah,1430
Minnie,1136
Helen,1097
Jane,985
Alice,985
Lou,947
Martha,920
Frances,914
Lily,873
Rose,865
Florence,746
Cora,733

(from this document.