Trotsky expelled from USSR

Lateran Treaty establishes independent Vatican City.

In U.S., stock market prices collapse, with U.S. securities losing $26 billion - first phase of Depression and world economic crisis.

St. Valentine's Day gangland massacre in Chicago.

Edwin Powell Hubble proposes theory of expanding universe.

US auto production hits 5,337,087; a record not surpassed until the 1950s.

First US diesel car - a Packard with a Cummins engine

First US front drive cars - Cord and Ruxton