She breaks down so much because she's old! That's what you have to keep telling yourself during your next frustrated bus commute, as today we are celebrating the Muni bus's 100th birthday. Yes, this day in history, September 1, 1917, the San Francisco Municipal Railway launched its very first bus line, the 1 Park. Motor coaches were a relatively new form of transportation at the time, and as the SFMTA explains in today's history lesson, Motor 01 connected the Geary streetcar line, via a route through Golden Gate Park to 9th and Judah and the Inner Sunset — a path that's still taken, in part, by the 44 O'Shaughnessy.

There were multiple companies serving the transportation needs of San Francisco at the time, and Muni was the first to venture into bus service, which was (and still is) the cheapest and easiest way to expand service because it doesn't require laying down tracks.

By the end of the 1920s, buses would already be a huge part of Muni's network — which by then had rail lines including the K Ingleside, L Taraval, and N Judah served by streetcars — and by the 1940s, they would have a fleet of 209 buses. (Last year we dug into the history of how Muni first began using electric trolly buses, way back in 1935.)

As part of this anniversary, Muni will be trotting out a bunch of vintage vehicles and mounting displays around town for Muni Heritage Weekend, September 9-10.

“Public transportation is what has kept San Francisco moving and developing for well over a century, and is more important today than ever,” says SFMTA director Ed Reiskin in a statement. “Our displays will show just how important Muni has been not only to the city’s past and present, but will also show its vital importance to San Francisco’s future.”

Per Mass Transit Magazine:

On September 9 and 10, from 10 a.m. to 5 p.m., San Franciscans and visitors can celebrate this double centennial by riding vintage Muni streetcars from the F-line Steuart Street stop (just a few hundred feet from the original J-line Ferry Building terminal), out Market Street and Church Street to the J’s original outer terminal at 30th Street and Church. The line will feature Harvey Milk Streetcar PCC 1051. Riders will enjoy spectacular views of the city from the top of Dolores Park.

Vintage buses built from 1938 to 1990 will operate on two routes, both departing from Market Street Railway’s San Francisco Railway Museum on Steuart Street between Market and Mission across from the Ferry Building. Two trolley coaches, 1950 Marmon-Herrington 776 and 1975 Flyer 5300, will run the route of the 41-Union line to Washington Square in North Beach.

Several vintage motor coaches will take turns transporting riders along the approximate route of the 82x line to Levi’s Plaza near the Cruise Ship Terminal at Pier 27. These buses include vintage 1938 White Motor Company gasoline coach 042, which served Coit Tower on the 39-line for almost 40 years. It is one of the oldest buses owned by a U.S. transit agency and is restored to its original orange and black Muni paint. It will be joined by 1970 GMC diesel bus 3287, familiar to many long-time San Franciscans for its red and yellow paint scheme, modeled after the California Street Cable Car livery. AM General motor coach 4154, built in 1984 and wearing its original livery created by famed San Francisco industrial designer Walter Landor, will also be in service, along with 1990 Orion coach 9010.

The special streetcars in service on Muni Heritage Weekend won’t just be limited to the J-line. One of America’s oldest streetcars, the 1896 “dinky” numbered 578, which a Muni predecessor ran along Oak and Page Streets before the 1906 earthquake and fire, will shuttle passengers along The Embarcadero between the F-line Steuart Street stop and Pier 39. It will be joined on that route by 103-year old Muni Car 130, bought to take San Franciscans to the 1915 Panama-Pacific International Exposition, and one of Muni’s popular 1934 vintage open-top “boat trams” acquired from Blackpool, England for Muni by Market Street Railway. Rides on these three streetcars will be free.

Additionally, there will be displays that weekend of vintage vehicles next to the Railway Museum, in the plaza on Steuart Street, and the Museum will be having a special sale on books and other memorabilia.

Related: A Brief History Of How San Francisco Ended Up With Electric Trolly Buses