The U.S. states have long been called "laboratories of democracy" (and not just by Republicans, as Bill Maher seems to imply in the clip below). The idea is that states can try different things and learn from each other's experience.
Of course, as with any experiment, it's necessary to take into account other possible causes for success or failure. Louisiana, for example, did suffer a bad economy under the policies introduced by Governor Bobby Jindal, whose approval ratings plummeted. But to be fair, those policies weren't the only cause; the drop in oil prices was a factor as well.
But the other examples Maher offers are pretty credible. Governor Brownback in Kansas really did push through conservative policies he assured voters would make the state boom and produce more tax revenues at lower tax rates. Instead, the state government is experiencing a financial crisis and the Kansas economy has been relatively dismal.
And it's true, as Maher says, that since the Democrats gained control of the entire state government in California and pushed through progressive policies, the state budget has gone from deficit to surplus surplus and the economy has grown so much that California, just by itself, is one of the world's largest economies. Almost exactly a year ago, an article in The Los Angeles Times noted that if it were an independent country, California's economy would be the eighth largest. And that's old news. The state has since then passed two more countries (India and France) to have the sixth largest economy on Earth and may soon be the fifth, especially if the British economy continues to fall in the wake of the Brexit vote to leave the EU.
See this Wikipedia article for more data on the gross domestic products of U.S. states and foreign countries. (Note that the numbers given are total, not per capita.)by