When you exit San Francisco supermarkets now, your groceries exit with you in paper or cloth bags. City leaders banned the use of plastic bags, for environmental reasons, making San Francisco the first city in the nation with such a ban.

California, meanwhile, has been trying to mandate the toughest vehicle emissions standards in the country. Recently, the Environmental Protection Agency said the state couldn’t do so. More than a dozen governors, including Washington’s Chris Gregoire, sent protests to the EPA.

No more plastic bags? Ultra-clean vehicles? Imagine. But remember when it seemed beyond imagination that states would ban smoking in bars? Or make it illegal to drive without seat belts?

In this era of federal government gridlock, it falls to cities and states to become laboratories for creative and landmark legislation.

Elected leaders in the Washington and Idaho legislatures are slogging through their sessions now. Slog is the right word, because change rarely happens quickly, even in state legislatures. The most creative ideas may die within a bill that never gets a hearing. But it often takes more than one session to pass laws that awaken citizens to a new way of thinking and living.

In 2006, for instance, Washington legislators finally passed a bill ending discrimination in housing, lending and employment on the basis of sexual orientation. Some legislators had been trying for 30 years to end this discrimination.

First-in-the-nation laws don’t always work as well as hoped. But the way first-in-the-nation cities and states grapple with their unique laws allows other cities and states to avoid similar mistakes – and improve on good ideas.

Last year, Massachusetts enacted a first-in-the-nation law requiring all citizens to buy health insurance, the way citizens in most other states are required to buy car insurance. The law went into effect in July. The Boston Globe reported last week that the mandate will cost the state about $400 million next year, because the number of people lacking state-subsidized insurance was much greater than expected.

Meanwhile, restaurant owners in New York are figuring out what business will be like when a trans fat ban goes into effect in July. And San Francisco shoppers no longer hear the checkout refrain: Paper or plastic?

In Washington’s Legislature this week, lawmakers are hearing the pros and cons of banning smoking in cars containing kids, outlawing small water bottles made with petroleum and confiscating the cars of those who troll the streets for prostitutes.

The laws being discussed right now in Olympia and Boise, and in farther away places such as California and Massachusetts, have the potential to change your daily habits, your business practices and your lifestyle choices. It’s wise to pay attention.