At 7:10 this evening, the California Zephyr Amtrak train bound for Chicago will quietly become the first train to use Denver Union Station’s new platforms, under the landmark white canopy. Following it, all Amtrak trains through Denver from now on will use Union Station instead of the temporary depot at 20th & Wewatta.

Although most of Union Station is still under construction, and not yet open to passengers, this marks the first major milestone in the opening of the station. For now Amtrak passengers will still use temporary facilities to wait, buy tickets, and retrieve luggage.

The underground bus terminal is expected to open in May, followed by the interior of the historic depot building in July. The first RTD trains aren’t scheduled to use the new platforms until 2016, when commuter rail begins service to the airport and other points north.