In 1905, Treynor was Incorporated! The first mayor was Ferdinand Schoening. The businesses at this time were Treynor Savings Bank, two general stores, a furniture & implement house, a livery stable, two saloons, several blacksmith shops, and a number of small places of business. The independent school had an enrollment of 4 pupils.
Early in 1910-1920, a high voltage electrical system was installed for $6,000. Before that, many homes were lit by a home electric plant or carbide lights.
On June 29, 1911, The Treynor Shortline railroad was dedicated. The cost to build this railroad, which was shut down five years later, was $300,000.
Early in the winter of 1919-1920, a terrible coal shortage hit the nation. Treynor, along with the rest of the states, went under the Garfield orders whereby all businesses opened at 9:00 a.m. and closed at 5:00 p.m., Saturdays excepted. Churches were to remain closed, except for a 3 hour service on Sundays. All social entertainments were called off and theaters, shows, dance halls, pool halls, bowling alleys, and other amusement places were ordered closed until further notice.
A new building for Treynor High School was dedicated in March of 1923. During this time, the price of a haircut was 50 cents.
In 1925, the population of Treynor was 223, compared to 204 in 1920. The current population is 919.