How do you date a drop leaf table with no markings?
Here is a picture of the bottom of it
Ask it out to dinner. Sorry, couldn't resist.
Check what kind of hardware was used. On you can date it by that. Just look up any site that has old screws hinges ect. If you think the hardware may have been changed look under the drop leaf and check the wood make sure that venner wasn't used look at the grain is it oak walnut hickory? One of the best things you should carry when shopping is a book on wood and old hardware. There are books on dishes markings porcelain , furniture of different ages ect. Many of them are paperback and easy to keep in your car. Watch Out for fakes they are often made of old wood but you can tell by the hardware mismatched wood width of wood [ especially in drawers]
A little familiarity goes along way .
Take lots of really good pictures, and have an antique dealer look at them.