Synodical Numbers

1922:There were 3,675,000 baptized Lutherans in the United States.

Of that total:

1,000,000 baptized members were in the Missouri Synod.
260,000 baptized members were in the Wisconsin Synod.
13,000 baptized members in the Slovak Synod.
6,500 baptized members in the Norwegian Synod.

The Missouri Synod consisted of 3,309 congregations and 858 preaching-stations, with a total of a little more than a million souls, served by nearly 2,500 pastors and professors and more than 1,000 schoolteachers.

1932:

The Missouri Synod consisted of 3,898 congregations and 906 preaching-stations, 1,189,000 souls, served by 3,127 pastors and 1,885 teachers.

The Wisconsin Synod (WELS) had 206,000 baptized members.
The Slovak Synod had 14,600 baptized members.
The Norwegian Synod had 7,300 baptized members.

From The Story of Our Church in America (Told in Simple Words). Th. Graebner. Concorda Publishing House, St. Louis, 1922 (and 1932 Supplement)