As it applies to ancient Mesopotamia and Egypt, how did the geography and environment in both locations affect the development of each culture’s economy, government, and religious practices?

Mesopotamia and Egypt are River Valley Civilizations—some of our earliest agricultural civilizations that centered around rivers. Mesopotamia, which means "between two rivers," was centered over the Tigris and Euphrates Rivers in modern-day Iraq. Egypt was centered on the Nile River. Both of these civilizations developed a specific way because of their location on a water source.
Economically, both civilizations had trade based on agriculture. Both the Nile and the Tigris/Euphrates Rivers allowed these civilizations to irrigate their lands and plant crops, like barley and millet. In turn, they were able to trade excess crops to other local peoples (and each other!) as an economy.
Politically, they developed differently. Egypt was a centralized state with their leader, the Pharaoh, in charge of all things. In Egypt, the state also directed the economy. There was government control over many aspects of daily life. They did this in order to control the flow of goods into and out of the State and also because the Pharaoh was considered to be a God. This is different from the Mesopotamians. In Mesopotamia, they were organized as city-states with their own rulers.
The most famous, Hammurabi of Babylon, was never considered a God like the Pharaohs of Egypt but was important in codifying laws and keeping the peace. The government did not have as large a role in controlling the economy, and merchants had some power in trading and selling. The city-state structure was adopted here in part because of the environment; Mesopotamia spread over a large, diverse area with different needs.
Religiously, they were both polytheistic. Many early civilizations adopted polytheism and worshiped gods related to aspects of their daily life, like the sun, death, food, fertility, and so on.

Both Mesopotamia and Egypt were fortunate to have rivers with cyclical flooding patterns that could be predicted. Mesopotamia, located in the Fertile Crescent, was between the Tigris and Euphrates Rivers. These rivers provided silt to fertilize the fields when they flooded. Early civilizations also used irrigation to provide water for crops during the dry season. The early religions of the area believed that the gods controlled the water.
Early governments were placed in charge of defending valuable cropland through war and trading surplus crops with other areas. Kings replaced priests over time; these kings soon made their reigns hereditary. The economy of Mesopotamia was improved by trade with other regions and conquest through war. The region was a major exporter of grain.
The ancient Egyptians, like the civilization in Mesopotamia, were quite dependent on floods to fertilize crops. The Nile's floods were cyclical, and the Egyptians were able to create a calendar in order to predict the floods. The gods controlled everything in this life and the next; the Egyptian pharaohs, in order to increase their power, declared themselves divine. In order to further proclaim their power, the pharaohs were placed in elaborate tombs with all the items needed for a happy afterlife.
The Egyptians placed a high value on education for its ruling classes, as it was important to chronicle grain harvests and laws for future generations. These hieroglyphics still line many burial sites in Egypt. Like the Mesopotamian culture, Egyptian culture also produced a lot of grain for export, but it was also able to take advantage of its position on the Mediterranean Sea. The Egyptians traded with and were commercial rivals with the Sea People, such as the Phoenicians.

Mesopotamia, whose civilization developed around 4,000-3500 BCE, was located between the Tigris and Euphrates Rivers, a fertile area (called the Fertile Crescent) that allowed for irrigation and the cultivation of crops. The development of agriculture allowed hunter-gatherers to settle down into permanent settlements and live in urban areas. The need for the upkeep of the cities along the rivers, as well as the construction of dams and other means to control the rivers, led to the development of government. Religion played a vital role in the development of government and urban areas, as gods were thought to be integral to the development of cities, and cities developed around ancient cult centers. Religious ziggurat structures were often located at the centers of cities. Around 3600 BCE, kings replaced priests as leaders and became the spokespeople of the gods.
In ancient Egypt, the people were dependent on the flooding of the Nile to grow and irrigate crops in an otherwise arid land. The dynastic period in Egypt began around 3100 BCE, when King Menes unified Upper and Lower Egypt and established his capital at Memphis near the Nile delta. The ability to grow surplus crops led to the development of a complex civilization that had a king (later a pharaoh) at its head, who controlled the agriculture and trade of the region. As the government developed in complexity, the vast bureaucracy collected taxes, maintained a system of justice, and recruited workers to grow certain crops and produce certain products as well as to carry out irrigation projects. The pharaohs of Egypt were regarded as divine and as intermediaries between people and the gods. The pharaohs were seen as critical in maintaining the support of gods to create an orderly universe.