NEW YORK — If you make it convenient for shoppers, they will come.

It’s estimated that U.S. shoppers hit stores and websites at record numbers over the four-day Thanksgiving weekend, according to a survey released by the National Retail Federation on Sunday. They were attracted by retailers’ efforts to make shopping easier, including opening stores on Thanksgiving evening, updating mobile shopping applications for smartphones and tablets, and expanding shipping and layaway options.

All told, a record 247 million shoppers visited stores and websites over the four-day weekend starting Thanksgiving, up 9.2 percent of last year, according to a survey of 4,000 shoppers that was conducted by research firm BIGinsight for the trade group. Americans spent more too: The average holiday shopper spent $423 over the entire weekend, up from $398. Total spending over the four-day weekend totaled $59.1 billion, up 12.8 percent from 2011.

The results appear to show that retailers efforts to make shopping effortless for U.S. consumers during the holiday shopping season worked. Retailers upped the ante in order to give Americans more reasons to shop at time when some of them are fearful about the weak job market and the potential that a wave of tax increases and budget cuts known as the “fiscal cliff” will take effect if Congress fails to reach a budget deal by January.

Retailers, which can make up to 40 percent of their online revenue in November and December, were hoping Americans would respond to incentives like the Thanksgiving openings, which enabled them to kick off the season earlier than ever. The National Retail Federation estimates that overall sales in November and December will rise 4.1 percent this year to $586.1 billion. That’s more than a percentage point lower than the growth in each of the past two years, and the smallest increase since 2009, when sales were nearly flat.