There are fifteen townships within DeKalb County's 370 square miles. The incorporated cities are: Auburn, 5,088, and Garrett, 4,428; towns: Butler, 1,643; Altona, 342; Corunna, 268; Saint Joe, 407, and Waterloo, 1,244. County populations: 1890, 24,307; 1900, 25,711; 1910, 25,054; 1920, 25,600; 1930, 24,911.

Auburn is situated twenty-three miles northeast of Fort Wayne and is served by two railroads. Two National and four State Highways criss-cross the county. The city's manufactured products include automobile tires, rubber soles, furniture, tool handles, cement blocks, rugs, harness, cigar lighters, cheese cutters, gasoline engines, furnaces, cigars, flour, and drugs. There is also a foundry, machine shop, and works for marble, vulcanizing, sheet metal, and bottling.

On the Courthouse ground in Auburn is a Soldiers' Monument, dedicated to the Spanish-American War veterans. The county has a number of other historical markers. In Spencerville a granite boulder with bronze tablet erected by the DeKalb County Historical Society marks the site of the first settlement in the county. There is a monument to the Civil War veterans in the cemetery at St. Joe. This memorial was erected in 1911 by the G. A. R. local post and the citizens of the vicinity. The post of the G. A. R. of Newville in 1893 placed a similar marker in their cemetery in memory of their Civil War veterans.

According to federal census figures of 1935, this county had twenty-four industries employing 842 wage earners, pay rolls for which totaled $841,717. The industrial produce value was $4,180,160.

The 2,360 farms in the county were valued at $10,624,228, the average size being 92 acres. A total of 65,090 head of livestock was reported.

The county's tax valuation for 1936 was $27,047,130.