A drop in charitable giving by Americans has been blamed on the continued decline in church attendance. 

Vanguard Charitable and the Lilly Family School of Philanthropy said in a new report that the number of adults giving to charity fell from two thirds in the year 2000, to just over half (53%) in 2016. 

This amounts to around 20 million fewer households giving to charity now than at the turn of the millennium. 

The report, "Changes to the Giving Landscape", draws on data from 9,000 families tracked by the University of Michigan in its Philanthropy Panel Study. 

Una Osili, co-author of the report and a researcher at the Lilly School, believes there are correlations between the fall in giving and a decline in religious practice in the US. 

"Attending services is correlated with giving to religious organizations, but it's also correlated with giving to secular groups," she said.

A Gallup poll earlier this year reported a significant drop in the proportion of Americans saying they attend worship at a church, synagogue or mosque. 

Only half of Americans said they belonged to a church or other religious institution, representing a 20 per cent fall over the last two decades and the lowest figure since Gallup starting polling on this question in 1937.

However, the Lilly School report also found that the challenging economic climate after the 2008 financial crisis impacted giving, particularly among lower income families. 

Jane Greenfield, president of Vanguard Charitable, said."This shift is due to lower-income and lower-wealth Americans experiencing the slowest economic recovery since the Great Recession, during years when the cost of other items such as food, education and healthcare have increased.

"This has led to a decrease in the share of income available to give to charity."