Vinho verde, the easy-drinking wine of northwestern Portugal, has become a welcome symbol of summer for many Americans.

Look at the numbers. In 2012, Portugal shipped almost 5.5 million bottles of vinho verde to the United States, according to the Portugal Global Trade and Investment Agency. On its own, that’s not a huge amount. But it’s well more than triple the 1.65 million bottles shipped 10 years ago.

We now see the wines frequently enough to warrant further investigation. So, at the end of May, the New York Times wine panel tasted 20 bottles of vinho verde.

What did we find? At their best, these wines are fresh and lively, zingy, zesty, sometimes fizzy and above all, untaxing. They are low in alcohol, generally 9 to 12.5 percent, and very low in price, with eight of our top 10 $10 and under.

I mention the time of the tasting because 16 of the 20 bottles came from the 2011 vintage — old by what was once the conventional standard, which holds that you would try to drink vinho verdes within a year of harvest.

Indeed, the name means green wine, suggesting not the color but that they are intended to be enjoyed in their energetic youth. But don’t get hung up on vintages: The 2011s we tasted were lively enough. While two of the three 2012s in our tasting were among our top three wines, I would not hesitate to drink a 2011.

The vinho verde region in northwestern Portugal lies flush on the Atlantic Coast, jutting inland like a left-hand mitten. Porto sits on its southwestern coastal edge, while the spectacular terraced vineyards of the Douro lie to the east of the region. While the Douro is protected from the Atlantic by hills and stays hot and dry, the vinho verde region receives the full brunt of the maritime influence.

Vinho verdes are traditionally made from a blend of unfamiliar grapes like arinto, azal, loureiro and trajadura, also known as treixadura in Spain. In recent years, more producers have been using the alvarinho grape, better known to Americans by its Spanish name albariño.

Vinho verdes are often thought to be mildly fizzy, and occasionally they are. The spritziness, historically a natural byproduct of fermentation but nowadays generally induced by injecting carbon dioxide, seemed to be random among the bottles we tasted. It’s a pleasant characteristic but not so crucial that you’ll miss it if it’s absent.

Tasting notes

Here are tasting notes on our top picks, in order of preference:

Vidigal Vinho Verde Shocking Green, 2011, $10: Tangy and refreshing with an inviting texture and crisp flavors of apple, citrus and nuts.

Vera Vinho Verde, 2012, $10: Fresh and lively, with clean, lingering mineral and citrus flavors.

Niepoort Vinho Verde Dócil Loureiro, 2012, $14: Aromas and flavors of citrus, apples and flowers, with more depth than many others.

Casa do Valle Vinho Verde, 2011, $10: Pleasant texture with flavors of tart citrus and pear.

J.M. Fonseca Vinho Verde Twin Vines, 2011, $8: Dry and inviting with aromas and flavors of citrus and flowers.

Gazela Vinho Verde, 2011, $5: Light, fresh and straightforward with floral and lemon aromas and flavors.

Adega de Moncao Vinho Verde Muralhas de Mono, 2011, $13: Lively and clean with zingy, tart citrus flavors.

Broadbent Vinho Verde, 2011, $9: Clean and balanced with pleasant texture and lively citrus flavors.

Joo Portugal Ramos Vinho Verde Lima Loureiro, 2011, $10: Tart, lively and straightforward with pleasing citrus flavors.

Fred Tasker’s wine column will return next week.