In the spring of 2014 there was a brief flurry of media stories claiming that the new mayor of Paris, Anne Hidalgo, had ordered a speed limit of 30 km/h (= 18.6 miles per hour) on all the streets of the city, excepting expressways.
In one blow this would have transformed Paris into the world’s safest and most livable large city — if it had been true.
What they really decided was more modest. On 19 May 2014 the Paris City Council adopted a resolution announcing their “intention” to increase the number of 30 km/h zones in the city, but they did not specify which or how many streets might be affected, nor did they give any dates.
One of the deputy mayors was quoted as saying that the resolution was a “general orientation in the form of a wish” and that major thoroughfares would not be affected, particularly not the Avenue des Champs-Élysées.
This is an important exception, because for French car fetishists (most of whom have out-of-town license plates, as Parisians are fond of pointing out) the Avenue des Champs-Élysées and the circle around the Arch of Triumph are highly symbolic and emotionally charged places. To thunder up the Champs-Élysées in an oversized car, screech to a halt at traffic lights and accelerate wildly when they turn green is considered the height of prestige in some circles. (See my posts It used to be even worse! and The triumph of cars over people.)
In her election campaign, the new mayor promised to re-allocate the space and calm the traffic at several major squares including the Place de la Bastille, but she was careful not to mention the Champs-Élysées or the Arch of Triumph.
As of December 2017, 45 % of the streets in Paris were already included in 30 km/h zones, but these were unequally distributed throughout the city. The eastern districts, which have socialist councils and mayors, have most of the 30 km zones. Nearly the entire 20th district is already limited to 30 km/h, with only a few major streets which allow higher speeds.

Paris districts after the 2014 elections (pink=socialist, blue=conservative, green=green)
The 2nd arrondissement, which has had a green-ecological mayor since 2001, is also well equipped with 30 and 20 km zones and large pedestrian areas. But 30 km zones are scarce in the western districts, which have conservative mayors. One of these, the 8th arrondissement, had no 30 km zones at all until 2018.
The plan now (approved by the city council in 2017) is that by 2020, traffic in the entire city — including the conservative eastern districts — will be limited to 30 km/h, with the exception of a few major thoroughfares. So those 2014 press reports weren’t completely wrong, just a few years early.

Two-way traffic on the boulevards
A significant improvement in Paris traffic went into effect in December 2012, when the Grands Boulevards (Montmartre, Poissonnière, Bonne-Nouvelle, Saint-Denis and Saint-Martin) were changed from five-lane one-way streets (which had functioned as high-speed “urban motorways” since 1951) to two-way streets with only three car lanes, two going west and one going east, plus a bus-and bike lane going west and a bike lane going east. This change was very well prepared, evidently, because even the conservative opposition, the taxi drivers and the local shopkeepers were in favor.

Cycling on the rearranged Grands Boulevards
My photos on this post are from 2014. I revised the text in 2019.
See also: Place de la République and Changes at Place de la Bastille.
This made me chuckle. With the high volumes of gridlock traffic I have often seen in Paris, I imagine simply reaching 30km/h would be a dream come true for many Parisian commuters! The scooters on the other hand.. they could certainly use a maximum speed. Don’t even get me started on my near-crashes with these on Paris sidewalks!
Due to the wishes of the left republican Ana Hidalgo of Cadiz Spain, Paris is going backward not only unimaginable laws on car traffic but also rollers, and bikes limited and with increase fines. At the same time the public transport is in bankrupt I know family works in maintenance and conductor of SNCF, now the short hauls flights of AF are been cancelled to force people to swich to the trains and help out their money situation. The 80 kph is now given choice to dept and region to leave them or eliminating them most will leave them. Paris is only now for visitors the real Parisien natives are leaving for my area or Bordeaux or Nantes and Paris is left to visitors and foreigners purchasing real high real estate to keep prices high. Ana I know her well, i do not agree with her then and now, she should do like her Spaniard Manuel Valls former prime minister of France who went back to his native Barcelona (where he lost the mayors’ office). Paris will never be the same and its showing. My five cents worth as French and Spanish citizen!